Af  ric.  Dent. 


Main  Lib. 


BIOLOGY 
r         LIBRAHK 


XI  A  N  l_J  A. 


HISTOLOCf  AND  BACTERIOLOGI 


INCLUDING 


A  CONCISE  STATEMENT  OF  THE  IMPORTANT  FACTS  OF 
MICROSCOPIC  TECHNIQUE  AND  URINALYSIS, 


A  LABORATORY  COURSE  OF  SEVENTY  PRACTICAL  EXERCISES 


PROVISION  FOR  NOTES  AND  DRAWINGS. 


BY 


WILLIAM  OSBURN,  A.  M. 

Professor  of  Histology,  Bacteriology,  and  Botany, 
Meharry  Medical  College. 


18W9, 

PRESS   OF   THE   MARSHALL  &  BRUCE   COMPANY, 
NASHVILLE,  TENN. 


COPYRIGHT,  1899, 

BY 

WILLIAM  OSBURN. 


TWO  COPIES  RECEIVED. 


COPY, 


CONTENTS. 


PAGE. 

PREFACE 5 

INTRODUCTION 7 

PART  1.— MICROSCOPY. 

CHAPTER            I. — Microscope  and  Accessories 8 

CHAPTER          II. — Microscopic  Technique 16 

CHAPTER        III. — Reagents  and  Stains 30 

PART  2.— HISTOLOGY. 

CHAPTER         IV.— The  Cell 35 

CHAPTER           V. — Tissues  and  Organs 53 

CHAPTER         VI.— The  Blood 55 

CHAPTER       VII. — Epithelial  Tissues  and  Endothelium  ..  61 

CHAPTER          VIII. — Connective  Tissues 66 

CHAPTER         IX. — Muscular  Tissues 75 

CHAPTER          X. — Nervous  Tissues  and  Systems 79 

CHAPTER         XI. — The  Circulatory  System 92 

CHAPTER       XII. — The  Lymphatic  System 96 

CHAPTER      XIII. — Membranes  and  Glands 100 

CHAPTER      XIV.— The  Skin . .  .... . 106 

CHAPTER       XV. — The  Alimentary  Canal Ill 

CHAPTER     XVI. — The  Liver 118 

CHAPTER    XVII.— The  Tongue  and  the  Teeth 121 

CHAPTER  XVIII. — The  Respiratory  System 127 

CHAPTER     XIX. — The  Kidney  and  Urinary  Tract 131 

CHAPTER       XX. — The  Genital  Organs 135 

CHAPTER     XXL— The  Eye,  Ear,  and  Nose 141 

PART  3.— BACTERIOLOGY. 

CHAPTER   XXII. — Characteristics    and    Classification     of 

Bacteria 143 

[3] 

268471 


4  CONTENTS. 

CHAPTER      XXIII. — Morphology,  Kinds,  and  Products. .  145 

CHAPTER      XXIV. — Size,  Numbers,  and  Distribution.  . .  149 
CHAPTER        XXV. — Cultivation  and  Systematic  Study  of 

Bacteria 151 

CHAPTER      XXVI. — Microscopic  Technique 156 

CHAPTER     XXVII. — Non-Pathogenic  Bacteria 160 

CHAPTER  XXVIII. — Pathogenic  Bacteria 164 

CHAPTER      XXIX. — Toxins,  Immunity,  Germicides,  etc. .  170 

PART  4.— URINALYSIS. 

CHAPTER        XXX. — Physical,  Chemical,  and  Microscopic 

Urinalysis 172 


PREFACE. 


This  modest  manual  has  been  prepared  by  the  writer  for  his 
classes  in  Histology  and  Bacteriology.  The  condensed  statement  of 
many  important  facts  of  these  subjects  will  be  appreciated  by  those 
who  have  a  limited  amount  of  time  for  their  study.  The  absence 
of  diagrams  may  be  a  disappointment  to  some  and,  at  first  thought, 
appear  as  a  disadvantage;  but  the  study  of  nature  is  primarily  the 
study  of  objects,  and  not  of  books  and  diagrams,  though  these  are  ad- 
mitted helps.  Its  end  should  be  the  interpretation  of  facts  and  the 
demonstration  of  truth,  and  this  is  accomplished  by  going  direct  to 
nature,  the  source  of  facts  and  the  embodiment  of  truth.  A  fact 
is  any  reality,  and  truth  is  the  correspondence  between  a  proposition 
and  a  reality — a  quality  rather  than  an  essence,  the  substantive  sug- 
gested by  the  adjective  true.  Not  every  proposition  is  true,  but 
every  reality  in  nature  embodies  a  truth.  When  we  prove  the  agree- 
ment between  a  proposition  and  the  real  thing  at  issue  we  demon- 
strate the  truth.  The  same  thing  is  accomplished,,  and  doubt- 
less a  higher  discipline  attained,  when  we  accurately  observe  a  re- 
ality of  nature  and  then  frame  a  proposition  that  truthfully  ex- 
presses that  reality.  One  of  the  highest  acts  of  the  human  mind  is 
correctly  to  observe  a  fact  and  accurately  state  the  truth  embodied 
in  that  fact.  A  diagram  may  embody  the  truth.  When  a  student 
correctly  interprets  nature  and  then  prepares  a  diagram  that  truth- 
fully represents  that  interpretation,  he  has  performed  an  act  of  the 
highest  disciplinary  and  practical  value.  Nothing  will  convey  to  the 
mind  of  the  teacher  a  student's  conception  of  a  subject  so  fully  as 
an  effort  on  the  part  of  that  student  to  represent  by  a  diagram  that 
which  he  observes.  It  is  well,  therefore,  to  encourage  students 
to  copy  nature  rather  than  the  conceptions  of  others,  even  though 
their  delineations  may  at  times  appear  crude.  The  motto  of  the 
teacher  should  be :  "  Nothing  goes  in  this  laboratory  without  draw- 


ings." 


[5] 


6  PREFACE. 

The  provision  made  for  drawings  in  this  manual  will  greatly  facil- 
itate that  work.  The  foot-notes  will  indicate  what  the  student  is 
to  observe  and  illustrate,  and  by  lettering  the  structures  drawn,  as 
indicated  in  the  descriptive  foot-note,  time  and  labor  will  be  saved. 
In  connection  with  this  work,  black-board  diagrams,  hand-made 
charts,  and  lantern  projections  can  be  used,  that  the  student  may 
have  the  clearest  possible  conception  of  what  the  microscope  reveals 
before  beginning  his  task  with  pencil  or  pen. 

A  word  to  the  student  will  not  be  amiss.  The  faithful  student 
will  not  be  content  to  let  another  do  his  work.  He  will  be  deter- 
mined to  make  every  demonstration  count.  He  will  strive  to  be  ac- 
curate in  his  observations  and  painstaking  in  his  notes  and  draw- 
ings. Blots,  finger  marks  and  erasures  will  be  studiously  avoided. 
In  the  laboratory  he  will  keep  everything  in  its  place  and  clean  up 
after  each  exercise.  He  will  not  be  satisfied  with  the  statements 
of  one  author,  but  will  seek  information  from  every  available  source. 
These  seem  minor  things,  but  they  enter  into  character.  Like 
straws,  they  show  the  direction  of  the  current. 

The  writer  desires  to  acknowledge  his  gratitude  to  kind  friends 
for  encouragement,  and  especially  to  Dr.  G.  W.  Hubbard,  Dean 
of  Meharry  Medical  College,  and  J.  H.  Holman,  M.D. ,  Instructor 
in  Histology  and  Bacteriology.  He  is  under  obligation  to  many 
sources  for  the  materials  herein  presented,  but  more  especially  to 
the  valuable  texts  of  Stirling  and  Piersol  on  Histology,  and  of  Mc- 
Farland  and  Williams  on  Bacteriology.  The  student  who  would  in- 
vestigate these  subjects  more  thoroughly  is  advised  to  secure  one  or 
more  of  these  works.  The  writer  is  aware  that  no  new  facts  are 
herein  presented,  and  is  fully  conscious  of  the  imperfections  and 
shortcomings  of  this  manual,  but  hopes  that  the  plan  proposed  will 
be  of  service  to  some,  and  with  this  hope  sends  it  forth  to  accom- 
plish its  purpose  among  others  of  kindred  nature. 

WILLIAM  OSBURN. 
NASHVILLE.  TENX.,  Aug-ust,  1899. 


INTRODUCTION. 


The  scope  of  this  manual  is  intended  to  cover  a  brief  statement  of 
the  important  facts  of  Microscopy,  Histology,  Bacteriology,  and 
Urinalysis. 

Microscopy,  in  a  liberal  sense,  is  the  microscopic  study  of  natural 
objects.  In  a  more  restricted  sense,  it  is  the  study  of  the  microscope, 
its  structure  and  manipulation,  and  of  microscopic  technique. 

Histology  is  that  department  of  Biology  which  treats  of  the  mi- 
nute anatomy  of  plants  and  animals.  Animal  Histology  deals  with 
the  microscopic  structure  of  animals ;  Vegetable  Histology,  with  that 
of  plants.  Animal  Histology  consists  of  two  departments — name- 
ly, Normal  Histology  and  Pathology.  Normal  Histology  deals  with 
cells  and  tissues  in  their  normal,  or  healthy,  state.  Pathology  deals 
with  these  structures  as  affected  by  disease.  There  is  an  intimate 
relation  between  Normal  Histology  and  Pathology.  Disease  affects 
the  cells,  and  the  student  must  understand  the  character  of  the  cells 
in  a  condition  of  health  before  he  can  adequately  comprehend  their 
pathological  condition. 

Bacteriology  is  that  department  of  Botany  which  treats  of  bac- 
teria— minute,  unicellular,  chlorophylless  fission-plants. 

Urinalysis  is  the  examination  of  the  urine  by  physical,  chemical, 
and  microscopical  tests,  by  means  of  which  its  normal  or  patholog- 
ical condition  is  determined. 

[7] 


I. 


MICROSCOPY. 


CHAPTEE  I. 
THE  MICROSCOPE  AND  ACCESSORIES. 

The  microscope  is  a  lens  or  combination  of  lenses  designed  to  aid 
the  eye  in  the  examination  of  minute  objects. 

KINDS  OF  MICROSCOPES. 

There  are  two  kinds  of  microscopes,  simple  and  compound.  A 
simple  microscope  is  a  single  lens  (or  group  of  lenses)  which  is  so 
used  that  the  object  to  be  examined  is  between  the  focus  and  the 
lens.  It  produces  an  erect  virtual  image.  A  compound  microscope 
is  a  combination  of  lenses,  by  means  of  which  an  inverted  image  is 
produced,  and  this  is  viewed  by  the  eye,  not  the  real  object. 

STRUCTURE  OF  THE  COMPOUND  MICROSCOPE. 

The  following  parts  should  be  carefully  studied,  and  the  use  of 
each  part  thoroughly  understood: 

The  base  rests  upon  the  table  and  supports  all  the  other  parts. 

The  pillar  is  the  upright  column  which  supports  the  arm. 

The  arm  is  attached  to  and  works  upon  the  pillar  by  means  of 
the  hinge-joint. 

The  reflector  is  the  mirror  by  which  the  object  to  be  examined  is 
illuminated. 

The  stage  is  the  platform  upon  which  rests  the  slide  containing 
the  preparation  to  be  studied.  Clips  are  springs  attached  to  the 
stage  to  hold  the  slide  in  position. 

The  aperture  is  the  circular  opening  in  the  stage. 

The  diaphragm  is  the  circular  disk  which  regulates  the  amount 
of  light  required  for  illumination. 

The  body  is  the  cylindrical  attachment  supported  by  the  arm. 

The  draw-tube  is  the  tube  which  moves  within  the  body. 
[8] 


THE  MICROSCOPE. 


9 


The  nose-piece  is  attached  to  the  lower  end  of  the  body  and  bears 
the  objectives. 

The  objective  is  the  lens  attached  to  the  body  or  nose-piece.  It 
often  consists  of  several  pieces  of  glass  cemented  together. 

The  objectives  commonly  used  are  the  two-thirds,  one-sixth,  and 
one-twelfth  inch.  By  a  two-thirds  inch  objective  is  meant  one  whose 
magnifying  power  is  equal  to  that  of  a  lens  whose  focal  length  is 
two-thirds  of  an  inch. 

The  eye-piece  comprises  the  lenses  which  fit  into  the  upper  end 
of  the  draw-tube.  It  contains  a  field-glass  and  eye-glass,  each  a 
piano  convex  lens,  with  the  convex  surface  downward. 

The  coarse-adjustment  consists  of  the  two  vertical  milled-heads 
and  the  rack  and  pinion. 

The  fine-adjustment  is  secured  by  the  horizontal  milled-head. 

Laboratory  exercise  No.  1. — Examine  a  compound  microscope  and 
make  out  each  part  named  above.  Make  a  study  of  the  diagram  on  page 
10. 


Substage  Attachment  with.  Condenser. 


Bausch  «k  Lomb  Optical  Co.,  Rochester,  N.  Y. 


MICROSCOPE,  SHOWING  PARTS. 


Bausch  &  Lomb  Optical  Co.,  Rochester,  N.  Y. 

Parts:  A,  base;  B,  pillar;  C.  arm;  D,  body;  E,  nose-piece;  F.  ojectives;  G-, 
eye-piece;  H,  draw-tube;  I,  collar;  J,  coarse-adjustment;  K,  milled-heads;  L, 
fine-adjustment;  M,  stage;  N,  clips;  O,  mirror;  P,  mirror-bar;  Q,  substage;  R, 
substagebar;  S,  diaphragm. 


THE  MICROSCOPE. 


11 


PHYSICAL  PRINCIPLES. 

The  image  produced  by  a  compound  microscope  is  a  magnified 
inverted  real  image.  Imagine  an  innumerable  number  of  lines 
proceeding  from  the  object  to  be  examined  in  a  direction  perpen- 
dicular to  the  long  axis  of  the  objective.  These  lines  represent  the 
rays  of  light  proceeding  from  all  points  of  the  object.  As  they  pass 
through  the  objective  they  are  bent,  or  refracted,  and  converged  to 
a  common  point  called  the  principal  focus.  No  image  is  produced 
at  this  focus.  The  accompanying  diagram  illustrates  how  this  focus 
is  produced. 


A  B,  object;  C,  lens;  F,  principal  focus. 

It  is  at  the  conjugate  foci  that  the  image  is  formed.  There  are 
as  many  conjugate  foci  as  there  are  emergent  points  on  the  sur- 
face of  the  object.  They  are  situated  between  the  principal  focus 
and  the  eye-piece.  Let  us  suppose  an  innumerable  number  of  emer- 
gent rays  of  light  to  have  proceeded  from  any  point  of  the  object. 
These  rays,  striking  the  lens  of  the  objective  upon  every  point 
of  its  surface,  are  refracted  and  converged  to  a  point  called  the 
conjugate  focus.  The  following  diagram  will  illustrate  how  the 


A  B,  object;  O,  objective;  A  and  B',  conjugate  foci;  E,  eye-piece;  A  B',  in- 
verted image  produced  by  the  objective;  A"  B"  magnified  inverted  image  viewed 
by  the  eye. 


12  MICROSCOPY. 

image  is  formed  at  the  conjugate  focus  and  hew  this  image  is  mag- 
nified by  the  eye-piece,  thus  producing  the  magnified,  inverted,  real 
image  which  is  viewed  by  the  eye  of  the  observer. 

MANIPULATION  AND  CARE  OF  A  MICROSCOPE. 

Handling. 

The  microscope  should  be  handled  with  more  than  ordinary  care. 
In  moying  it  from  place  to  place  it  should  be  caught  firmly  by  the 
pillar.  Reagents  of  any  kind  should  not  be  allowed  to  come  in  con- 
tact with  it.  Alcohol  will  destroy  the  lacquer,  and  acids  will  pro- 
duce corrosion  of  its  surface.  The  hands,  therefore,  should  be  kept 
perfectly  clean. 

Cleansing. 

The  microscope  may  be  cleaned  with  a  linen  cloth.  Reagents 
should  not  be  used  in  cleansing  the  objectives  and  eye-piece  without 
the  direction  of  the  teacher.  To  remove  balsam  from  the  objective, 
alcohol  or  xylol  may  be  used,  but  should  be  quickly  removed  with 
Japanese  paper,  a  soft  paper  especially  used  for  cleaning  lenses. 

Obtaining  a  Focus. 

To  obtain  a  focus,  place  the  slide  upon  the  stage  so  that  the  ob- 
ject to  be  examined  appears  in  the  center  of  the  aperture;  adjust  the 
reflector  so  as  to  illuminate  the  object.  Lower  the  objective  by 
means  of  the  coarse-adjustment  until  it  is  below  the  focal  point; 
then,  with  the  eye  at  the  eye-glass,  work  upward  until  the  object  ap- 
pears, making  the  focusing  perfect  by  means  of  the  fine-adjustment. 

Cautions. 

To  save  harm  to  the  eyes  in  the  use  of  the  microscope  it  is  a  good 
plan  to  keep  both  eyes  open;  let  the  eye  be  used  as  though  viewing 
some  distant  object;  there  should  be  no  conscious  strain  to  obtain  a 
focus,  but  let  the  hand  with  fine-adjustment  aid  the  eye ;  do  not  use 
the  microscope  long  at  a  time,  so  as  to  produce  an  aching  sensation 
in  the  eye. 

Allow  nothing  to  touch  the  lenses,  except  Japanese  paper  or  soft 
linen,  which  may  be  used  in  cleaning  them. 


THE  MICROSCOPE.  13 

ACCESSORIES. 

The  sub-stage. — This  is  an  attachment  supported  beneath  the 
stage  and  is  designed  to  receive  the  iris  diaphragm,  Abbe  condenser, 
.etc. 

Iris  diaphragm. — This  is  supported  by  the  sub-stage  and  is  so 
constructed  that  the  aperture  for  admitting  light  may  be  regulated 
by  turning  a  milled-head. 

Abbe  condenser. — This  is  an  apparatus  containing  a  lens  of  very 
short  focus,  and  is  capable  of  producing  intense  illumination.  It 
is  supported  by  the  sub-stage. 

Mechanical  stage. — This  is  attached  to  the  microscope  so  as  to 
work  above  the  stage,  and  is  designed  to  hold  the  slide  and  so  change 
its  position  as  to  bring  every  part  of  the  object  into  the  field  of  view. 

Camera  Lucida. — This  is  an  apparatus  which  is  attached  to  the 
tube  of  the  microscope,  and  is  designed  to  assist  in  making  diagrams 
of  the  object  .studied. 

Polariscope. — Polarization  consits  in  reducing  vibrations  of  light 
to  one  plane.  This  is  accomplished  by  the  polariscope,  which  con- 
sists of  a  polarizer  and  an  analyzer.  The  polarizer  consists  of  a 
crystal  of  Iceland  spar,  which  by  double  refraction  separates  the  or- 
dinary from  the  extraordinary  ray.  The  analyzer  generally  used  is  a 
Nicol's  prism,  which  consists  of  a  crystal  of  Iceland  spar  split  diag- 
onally and  the  pieces  then  cemented  together  with  Canada  balsam. 
The  Canada  balsam  produces  the  total  reflection  of  the  ordinary  ray, 
while  the  extraordinary  ray  passes  through.  The  analyzer  is  used 
to  detect  polarized  light. 

Micrometer. — There  are  two  kinds  ofmicrometers — the  stage  mi- 
crometer and  the  eye-piece  micrometer.  The  stage  micrometer  is 
a  small  glass  slide,  upon  which  is  a  graduated  scale,  the  graduations 
being  in  millimeters  and  tenths  of  a  millimeter.  It  is  used  in  de- 
termining the  magnifying  power  of  the  microscope. 

Laboratory  exercise  No.  2. — To  obtain  a  focus.  Place  upon  the  stag-e 
a  prepared  slide;  adjust  the  reflector  so  as  to  illuminate  the  object; 
using-  first  the  low  power,  by  means  of  the  coarse-adjustment  lower 
the  objective  until  it  is  below  the  focal  point.  If  the  objective  be  a 
two-thirds  inch,  the  focal  point  will  be  somewhat  less  than  two-thirds 
of  an  inch  from  the  object.  Now,  with  the  eye  at  the  eye-piece  work 
upward  until  the  object  appears  in  view^  Perfect  the  focusing-  by  using- 


14  MICEOSCOPY. 

the  fine-adjustment.  When  using-  the  microscope  it  is  always  a  good 
plan  to  keep  the  hand  upon  the  fine-adjustment,  using-  it  constantly 
to  bring-  different  planes  of  the  object  into  the  field  of  vision. 

To  determine  the  magnifying  power.  Place  upon  the  stage  a  stage-mi- 
crometer and  focus  with  both  eyes  open.  The  lines  upon  the  microm- 
eter will  also  be  seen  by  the  eye  not  in  use.  Place  under  the  microscope 
or  upon  the  stage  a  sheet  of  white  paper.  Now,  with  a  pencil  mark 
the  apparent,  or  magnified,  distance  between  two  lines.  Knowing  the 
real  distance,  one-tenth  of  a  millimeter,  the  magnification  can  readily 
be  determined.  For  example,  should  the  magnified  distance  between 
two  lines  be  thirty  millimeters,  the  real  distance  being  one-tenth  of 
a  millimeter,  the  magnification  would  therefore  be  ten  times  thirty, 
or  300. 

Microtome. — The  microtome  is  an  apparatus  employed  in  cutting 
microscopic  sections  of  tissues.  It  is  provided  with  a  microtome 
knife,  a  knife-carrier,  and  the  milled-head  which  operates  a  mechan- 
ism for  regulating  the  thickness  of  the  sections.  The  student  micro- 
tome manufactured  hy  the  Bausch  &  Lomb  Optical  Company,  of 
Eochester,  N.  Y.,  is  a  most  excellent  instrument  for  all  ordinary 
work. 

Paraffin  Bath. — This  is  designed  for  use  in  infiltrating  and  em- 
bedding tissues  in  paraffin.  The  heat  should  be  so  regulated  as 
to  keep  the  paraffin  as  near  the  melting  point  as  possible.  Where 
gas  is  available  this  may  be  accomplished  by  means  of  a  thermostat. 

Cornet  Forceps. — This  is  a  forceps  especially  useful  in  holding 
cover-glasses  when  staining  preparations  of  sputum,  bacteria,  etc. 

Centrifuge. — This  apparatus  utilizes  the  centrifugal  tendency 
and  is  employed  to  separate  substances  of  different  specific  gravity. 
It  is  provided  with  two  important  attachments,  the  sedimentation 
tubes  and  carrier  and  the  haematokrit.  The  sedimentation  tube 
contains  fifteen  cubic  centimeters  and  is  graduated  into  100  equal 
parts,  up  to  ten  cubic  centimeters,  and  above  that  each  cubic  centi- 
meter is  graduated  into  four  equal  parts  for  the  measurement  of  re- 
agents employed.  Tty  means  of  these  the  solid  matter  in  urine, 
water,  etc.  may  be  precipitated  and  the  exact  per  cent  determined. 

The  haematokrit  is  provided  with  graduated  tubes;  each  tube  is 
fifty  millimeters  in  length  and  is  divided  into  100  equal  parts.  The 
diameter  of  the  bore  is  0.5  millimeter.  These  tubes  are  used  in  deter- 
mining the  percentage  composition  of  the  blood.  By  revolving  the 
handle  of  the  centrifuge  seventy-seven  times  in  a  minute  the  haema- 


THE  MICROSCOPE.  15 

tokrit  is  caused  to  rotate  5,000  times.  This  rapid  rotation  precipitates 
to  the  outer  end  of  the  tube  the  red  blood  corpuscles,  which  are  of 
the  highest  specific  gravity.  Next  to  these  will  be  arranged  the  white 
corpuscles,  which  are  heavier  than  the  plasma,  while  the  plasma 
fills  the  remaining  portion  of  the  tube.  A  tube  is  also  provided  for 
sputum,  by  means  of  which  bacteria  may  be  precipitated,  thus  in- 
creasing the  accuracy  of  a  microscopic  analysis. 

Slide  and  Cover-glass. — The  slide  consists  of  a  piece  of  glass  one 
inch  wide  and  thige  inches  long,  and  is  used  to  receive  the  object 
to  be  examined.  The  cover-glass  is  a  thin  piece  of  glass,  rectangular 
or  circular  in  shape.  In  cleaning  slides  and  cover-glasses,  tissue  paper 
or  a  linen  towel  may  be  used.  They  should  always  be  seized  by  their 
edges,  never  allowing  the  fingers  to  touch  the  flat  surfaces. 


Student  Microtome. 


Bausch  &  Lomb  Optical  Co.,  Rochester,  N.  Y. 

NOTE. — Nearly  all  the  illustrations  of  this  manual  are  from  electro- 
types kindly  loaned  the  author  by  the  Bausch  &  Lomb  Optical  Company, 
of  Rochester,  N.  Y.  Students  and  others  desiring  to  purchase  micro- 
scopes and  microscopic  supplies  will  find  this  firm  courteous  in  its  deal- 
ing's. The  goods  sent  out  by  this  house  are  reasonable  in  price  and  first- 
class  in  quality. 


16  MICROSCOPY. 


CHAPTER  II. 

MICROSCOPIC  TECHNIQUE. 
I.  THE  HISTORY  OF  THE  SLIDE. 

The  history  of  a  slide  from  the  crude  tissue  to  the  finished  mount 
includes  the  following  processes :  Fixing,  hardening,  infiltrating,  em- 
bedding, sectioning,  fixation,  staining,  dehydrating,  clearing, 
mounting,  labeling. 

1.  Fixing.— This  process  consists  in  so  killing  the  cells  as  to  pre- 
serve them  in  their  natural  form  and  structure.    The  reagents  com- 
monly used  for  this  purpose  are  alcohol,  corrosive  sublimate,  chromic 
acid,  Perenyi's  fluid,  etc.     To  fix  tissues  in  absolute  alcohol,  they 
should  be  allowed  to  remain  from  one  to  six  hours,  according  to  the 
character  of  the  specimen.    Objects  are  left  in  Perenyi's  fluid  from 
three  to  twelve  hours  and  then  transferred  to  seventy  per  cent  al- 
cohol.   Specimens  hardened  in  corrosive  sublimate  solution  should 
be     removed     in     one     to     three     hours,     according     to     size. 
To    fix    tissue    in    chromic    acid    requires    from    a    few    days 
to  a  few  weeks.    After  fixing  in  the  last  reagent,  the  tissue  should 
be  thoroughly  washed  with  water  and  then  run  through  increasing 
strengths  of  alcohol  in  the  dark.     Picro-sulphuric  Acid,  Erlicki's 
Fluid,  Muller's  Fluid,  and  Flemming's  Solution  are  also  commonly 
used  for  this  purpose. 

2.  Hardening.— This  consists  in  dehydrating  the  tissues  so  as  to 
make  them  rigid  and  suited  for  sectioning  with  the  microtome.    For 
this  purpose  alcohol  is  commonly  used.    The  tissue  should  be  run 
through  increasing  strengths — seventy  per  cent,  eighty  per  cent, 
ninety  per  cent,  ninety-five  per  cent,  and  absolute  alcohol.    Objects 
should  not  be  allowed  to  remain  long  in  absolute  alcohol  (from  one 
to  five  hours),  as  this  renders  the  tissue  brittle  and  causes  it  to  crum- 
ble under  the  knife  of  the  microtome.    The  objects  may  remain  in 
the  other  strengths  of  alcohol  about  twenty-four  hours  for  each. 

3.  Infiltrating. — This  process  consists  in  removing  the  hardening 
agent  and  filling  up  the  pores  of  the  tissue  with  an  embedding  me- 


MICROSCOPIC  TECHNIQUE.  17 

drum.  As  soon  as  the  object  is  removed  from  absolute  alcohol  it 
should  be  thoroughly  dried  with  blotting  paper.  If  it  is  desired  to 
embed  with  paraffin,  the  specimen  should  be  placed  in  xylol,  chloro- 
form, turpentine,  or  cedar  oil  for  at  least  twelve  hours,  and  then 
transferred  to  a  solution  of  paraffin  and  xylol,  allowing  it  to  remain 
twelve  to  twenty-four  hours.  It  may  now  be  transferred  to  melted 
paraffin,  which  should  be  kept  as  little  above  the  melting  point  as 
possible.  After  remaining  until  it  becomes  thoroughly  saturated 
with  the  paraffin,  which  usually  requires  from  twelve  to  twenty- 
four  hours,  it  may  then  be  embedded.  To  infiltrate  with  celloidin, 
two  solutions  are  necessary,  a  thin  and  a  thick.  The  celloidin  is  dis- 
solved in  equal  parts  of  absolute  alcohol  and  ether.  To  make  the 
thin  solution,  use  five  grams  of  celloidin  in  100  cc.  of  the  mixture. 
The  second  solution  should  have  the  consistency  of  thick  sirup.  The 
dehydrated  tissue  is  placed  in  a  mixture  of  equal  parts  of  absolute 
alcoHol  and  ether  from  twelve  to  forty-eight  hours,  then  in  the  thin 
solution  for  about  the  same  period.  It  may  remain  in  the  thick 
solution  twenty-four  hours,  or  longer  if  desired.  It  is  then  ready  for 
embedding. 

4.  Embedding  in  paraffin — Embedding  L's  or  paper  boxes  may  be 
used.  To  accomplish  this  process,  the  following  method  may  be 
pursued:  Place  upon  a  pane  of  glass  a  clean  piece  of  paper.  Ar- 
range the  embedding  L's  so  as  to  form  a  receptacle  of  the  required 
size.  Pour  into  this  a  small  quantity  of  melted  paraffin.  Now  ar- 
range the  tissue  in  the  position  desired  and  fill  the  receptacle  with 
paraffin.  As  soon  as  the  paraffin  becomes  sufficiently  hardened  the 
embedding  L's  may  be  set  in  a  vessel  containing  ice-cold  water.  Care 
should  be  taken  that  the  water  does  not  run  over  the  top  of  the 
paraffin. 

To  Embed  with  Celloidin. — A  cork  or  block  of  wood  which  has 
been  soaked  in  equal  parts  of  absolute  alcohol  and  ether  may  be 
used.  Place  upon  the  cork  or  block  a  small  quantity  of  thick  cel- 
loidin.. Then  place  in  position  the  piece  of  tissue  and  cover  it  with 
the  celloidin,  adding  a  little  at  a  time,  layer  after  layer  as  each 
hardens,  until  the  tissue  is  completely  embedded.  The  whole  may 
now  be  transferred  to  chloroform  for  one  or  two  hours,  and  then 
to  seventy-five  per  cent  alcohol,  where  it  may  be  left  indefinitely. 
2 


18  MICROSCOPY. 

5,  Sectioning. — This  consists  in  cutting  thin  sections  of  the  ob- 
ject to  be  examined.    It  is  accomplished  by  the  use  of  a  razor,  or  mi- 
crotome knife,  which  may  be  used  free-hand  or  with  a  microtome. 
To  cut  paraffin  sections,  first  pare  the  block  to  the  right  size  and  then 
fasten  it  in  the  clamp  of  the  microtome.     The  paraffin  should  be 
kept  at  the  right  temperature.    This  may  be  accomplished  by  using 
cold  or  hot  water,  applying  it  with  a  camelVhair  brush,  or  with  the 
heat  of  the  hand  or  a  flame.    The  knife  should  be  drawn  at  a  slight 
angle.     If  sections  curl,  they  may  be  placed  upon  the  surface  of 
moderately  warm  water  to  flatten  them.    Curling  may  be  prevented 
by  holding  the  sections  in  place  with  a  cameFs-hair  brush  as  they 
are  cut. 

Celloidin  sections  are  cut  in  the  same  way,  with  the  exception 
that  the  knife  and  celloidin  block  must  be  kept  constantly  flooded 
with  seventy-five  per  cent  alcohol.  The  sections  when  cut  may  be 
removed  to  a  vessel  containing  seventy-five  per  cent  alcohol,  and 
there  kept  indefinitely. 

6.  Fixation. — This  consists  in  attaching  sections  to  the  slide. 
Paraffin  sections  may  be  affixed  with  collodion  mixture,  or  with  egg- 
albumen  and  glycerine.    To  affix  with  collodion,  make  a  thin  layer 
with  camelVhair  brush  upon  the  slide.     Then  apply  the  section, 
flattening  it  out  with  finger  or  brush;  now  apply  the  heat  of  a  spirit 
or  Bunsen  flame  until  the  paraffin  melts,  being  careful  to  avoid 
excessive  heating,  such  as  would  injure  the  tissue.     To  affix  with 
egg-albumen  and  glycerine,  a  thin  coating  is  made  with  a  camel's- 
hair  brush,  and  the  section  is  then  transferred  to  the  center  of  the 
slide,  care  being  taken  to  flatten  it  out  with  finger  or  brush.    Heat 
is  then  applied  to  coagulate  the  albumen.     To  avoid  overheating, 
the  slide  should  be  frequently  applied  to  the  surface  of  the  hand. 
When  the  paraffin  becomes  thoroughly  melted  the  section  is  usually 
properly  affixed. 

If  desired  to  affix  celloidin  sections,  a  drop  of  ether  may  be  ap- 
plied to  each  section  after  placing  it  in  the  desired  position,  or  they 
may  be  affixed  with  the  collodion  and  clove-oil  mixture  in  the  fol- 
lowing manner :  Apply  a  thin  layer  of  collodion  mixture  to  center  of 
slide ;  when  the  collodion  is  dry  apply  the  section,  together  with  the 
thin  piece  of  paper  upon  which  it  has  been  placed,  and  press  upon 


MICROSCOPIC  TECHNIQUE.  19 

the  whole  with  a  dry  blotting  paper.  The  section  will  now  adhere 
and  the  paper  may  be  removed.  Now  cover  the  section  with  a  thin 
layer  of  collodion  mixture,  and  it  will  be  thoroughly  affixed. 

Centering. — The  process  of  fixation  should  also  include  the  cen- 
tering of  the  section.  This  may  readily  be  accomplished  by  means 
of  a  diagram  of  the  slide,  which  may  be  drawn  upon  the  under  sur- 
face of  the  cover  of  a  mailing  box.  See  laboratory  exercise  No.  3. 

7.  Staining. — This  process  consists  in  tinting  the  structures  of  the 
section  with  certain  stains,  so  as  to  produce  a  differentiation  of  the 
different  elements  and  render  them  more  readily  studied.     It  de- 
pends upon  the  principle  that  certain  structures  have  an  affinity  for 
certain  stains,  but  not  for  others.     For  example,  a  stain  that  will 
affect  the  protoplasm  and  nucleus  may  have  no  effect  upon  the  cell- 
wall.    A  stain  that  will  affect  certain  cells  may  have  no  effect  upon 
others.    Haematoxylin  will  stain  the  leucocytes,  but  not  the  red  cor- 
puscles.    Eosin  will  stain  the  red  corpuscles,  but  not  the  white. 
Staining  should  always  be  preceded  by  certain  processes  so  as  to 
prepare  the  tissue  to  receive  it.    First,  if  a  paraffin  section  is  to  be 
stained,  the  paraffin  must  be  removed.     This  is  accomplished  by 
immersing  it  in  xylol,  turpentine,  chloroform,  or  benzole.     These 
reagents  dissolve  out  the  paraffin.    The  xylol,  etc.,  may  then  be  re* 
moved  by  applying  alcohol.     Should  an  aqueous  solution  of  any 
stain  be  used,  the  section  should  be  washed  with  water  before  ap- 
plying the  stain,  and  followed  with  the  same.    If  the  stain  be  alco- 
holic, its  application  should  be  preceded  and  followed  by  alcohol  of 
the  same  strength.     The  different  staining  methods  are  given  on 
page  23. 

8.  Dehydrating. — This  consists  in  the  removal  of  water  from  the 
specimen,  water  being  generally  the  enemy  of  the  histologist.     It 
is  accomplished  by  running  the  section  through  increasing  strengths 
of  alcohol,  using  first  an  alcohol  of  the  same  strength  as  the  stain- 
ing solution.    The  object  of  this  is  to  prevent  the  precipitation  of  the 
stain,  by  which  the  preparation  becomes  filled  with  dark  granular 
masses. 

9.  Clearing.— This  consists  in  the  removal  of  the  alcohol  so  as  to 
prepare  the  sections  for  balsam  and  in  so  clearing  up  the  section  as 
to  render  it  transparent.    By  closely  observing  the  change  in  color 


20  MICROSCOPY. 

or  by  placing  the  finger  nail  beneath  the  section,  the  student  can  de- 
termine whether  the  process  is  complete.  The  reagents  commonly 
used  for  clearing  purposes  are  creosote,  cedar  oil,  xylol,  benzole, 
clove  oil,  and  aniline  oil. 

10.  Mounting   consists    in    permanently    attaching    the    cover- 
glass  for  the  protection  of  the  specimen.     Balsam  and  glycerine- 
jelly  are  generally  used  for  this  purpose.    For  laboratory  work  the 
balsam  method  will  be  found  the  most  convenient.    Place  upon  the 
cover-glass,  while  holding  it  between  the  fingers,  a  drop  of  balsam, 
and  then  (balsam  down)  let  it  fall  gently  upon  the  section.    After 
centering  the  cover-glass,  apply  gentle  pressure  by  means  of  a  dis- 
secting needle,  so  as  to  force  the  balsam  out  to  the  edges  of  the  glass. 
Should  too  much  balsam  be  used,  it  may  be  removed  (when  thor- 
oughly dried)  with  a  pen-knife.     This  method  will  be  found  more 
satisfactory  than  to  undertake  its  removal  with  cloth  or  brush  by 
means  of  xylol.    The  safest  plan  is  to  use  just  enough  balsam,  no 
more,  no  less. 

11,  Labeling. — Two  labels  should  be  used,  one  on  each  end  of  the 
slide,  and  they  should  be  so  applied  that  the  edges  of  the  labels  will 
be  the  same  distance  from  the  edges  of  the  slide.    The  left  hand  label 
should  indicate  the  number  of  the  preparation,  the  staining  fluid, 
the  mounting  medium,  the  date,  and  the  name  of  the  student.    The 
right  hand  label  should  indicate  the  kind  of  tissue,  the  character  of 
the  section  (whether  transverse,  longitudinal,  vertical,  or  oblique), 
the  condition  of  the  specimen  (whether  normal  or  abnormal),  and 
the  animal  from  which  it  has  been  obtained.     After  labeling,  the 
preparation  should  be  placed  in  the  slide-box  in  a  horizontal  posi- 
tion, with  the  cover-glass  up,  and  kept  in  that  position  until  the  bal- 
sam hardens. 

II.  SPECIAL  TREATMENT  OF  TISSUES  AND  ORGANS. 

The  structures  required  for  microscopic  work  may  be  obtained 
from  some  animal,  such  as  the  cat,  rabbit,  or  guinea  pig.  Should  a 
cat  be  used,  it  may  be  killed  by  placing  it  under  an  inverted  bowl 
(resting  upon  a  heavy  sheet  of  paper  upon  a  table  or  floor),  and  then 
inserting  a  sponge  saturated  with  chloroform.  In  twenty  minutes 
the  animal  will  be  dead  and  ready  for  injection. 

Injecting. — To  inject  the  animal,  the  following  process  may  be 


MICROSCOPIC  TECHNIQUE.  21 

pursued:  Sever  the  costal  cartilages  on  each  side  of  the  sternum; 
lift  up  the  sternum  and  bend  it  forward  so  as  to  expose  the  heart. 
Make  a  slit  into  the  right  auricle  to  allow  the  escape  of  the  blood. 
Snip  off  the  end  of  the  heart  and  slit  open  the  left  ventricle-  Insert 
the  canula  of  the  injecting  syringe  into  the  aorta,  carefully  tying  the 
same  upon  the  end  of  the  canula.  Now,  having  filled  the  syringe 
with  normal  saline  solution  at  body  temperature  and  having  filled 
the  canula  with  the  same,  using  pipette,  attach  the  two,  and  with 
a  gentle  pressure  force  the  liquid  through  the  system  until  the  ar- 
teries and  veins  have  been  thoroughly  relieved  of  blood.  Eepeat  the 
same  process,  using  Carter's  Carmine  Mass.  By  observing  the  lips 
and  other  structures  it  can  be  determined  when  the  circulatory  sys- 
tem is  filled  with  the  injecting  fluid.  ISTow,  make  a  ligature  around 
the  aorta,  just  beyond  the  canula,  and  the  syringe  can  be  removed. 
In  fifteen  minutes  the  tissues  can  be  cut  up  into  small  blocks  (these 
blocks  should  be  in  the  form  of  cubes  or  rectangles  from  1  cc.  to  2 
cc.  in  size),  and  placed  in  the  fixing  fluids. 

Epithelium. — For  purposes  of  study  epithelium  may  be  obtained 
from  the  casts  of  a  frog  or  newt,  from  the  scrapings  of  the  human 
lip,  from  the  throat  of  a  frog,  and  the  scrapings  of  the  trachea  of  a 
pig.  This  material  may  be  readily  obtained  by  macerating  the  ob- 
ject in  weak  alcohol.  Keep  the  specimens  in  eighty  per  cent  al- 
cohol, and  use  when  required. 

Cartilage. — Fix  in  absolute  alcohol;  harden  with  increasing 
strengths  of  alcohol,  and  embed  in  paraffin.  Stain  with  carmine. 

Mucous  Tissue. — Fix  small  pieces  of  the  umbilical  cord  with  ab- 
solute alcohol,  harden  with  alcohol,  embed  in  celloidin,  and  stain 
with  hsematoxylin. 

Bones  and  Teeth. — Fix  in  ninety-five  per  cent  alcohol  three  days; 
decalcify  in  a  saturated  aqueous  solution  of  picric  acid  or  in  a  ten 
per  cent  solution  of  nitric  acid.  This  process  will  require  from  five 
to  ten  days.  When  the  bone  or  tooth  is  thoroughly  softened,  trans- 
fer to  ninety-five  per  cent  alcohol,  changing  in  three  days  to  fresh 
alcohol.  Embed  in  celloidin.  Specimens  embedded  in  paraffin 
should  not  be  overheated. 

Muscle. — Fix  in  absolute  alcohol;  harden  with  increasing 
strengths  of  alcohol ;  embed  in  paraffin ;  stain  with  lithium  carmine. 


22  MICROSCOPY. 

The  muscle  of  a  salamander  will  be  found  excellent  for  demonstrat- 
ing the  structure  of  the  fibers. 

Brain  and  Spinal  Cord. — Fix  and  harden  in  Muller's  fluid  or 
Erlicki's  fluid,  two  weeks  for  the  former  and  fifteen  days  for  the 
latter.  Wash  thoroughly  in  water  before  embedding,  which  may  be 
done  in  paraffin. 

Heart. — Fix  in  absolute  alcohol;  harden  with  alcohols;  embed  in 
paraffin;  stain  with  haematoxylin. 

Blood  Vessels. — Fix  and  harden  with  alcohol;  embed  in  paraffin 
or  celloidin;  and  stain  with  lithium  carmine  or  haematoxylin  and 
eosin. 

Lymphatic  Glands. — Fix  and  harden1  with  alcohol ;  embed  in  cel- 
loidin ;  and  stain  with  haematoxylin  and  eosin. 

Skin. — Fix  and  harden  with  alcohol;  embed  in  paraffin;  and 
stain  with  haematoxylin  and  eosin. 

The  Spleen. — Fix  and  harden  with  alcohol;  embed  in  paraffin; 
stain  with  haematoxylin  and  eosin. 

(Esophagus. — Fix  with  corrosive  subliniate  or  Perenyi's  fluid; 
harden  with  alcohol ;  embed  in  paraffin ;  and  stain  with  haematoxy- 
lin  and  eosin. 

Stomach. — Fix  with  corrosive  sublimate;  harden  with  alcohol; 
embed  with  paraffin  or  celloidin ;  stain  with  haematoxylin. 

Intestine. — Fix  with  corrosive  sublimate;  harden  with  alcohol; 
embed  in  celloidin ;  stain  with  hgematoxylin  and  eosin. 

Tongue. — Fix  with  absolute  alcohol ;  harden  with  alcohols ;  embed 
in  paraffin :  and  stain  with  haematoxylin  and  eosin. 

Trachea. — After  filling  the  trachea  and  lungs  with  a  two-tenths 
per  cent  solution  of  chromic  acid,  suspend  them  in  a  large  volume  of 
the  same  for  two  days ;  then  cut  into  small  pieces  and  place  in  two- 
tenths  per  cent  of  chromic  acid  for  two  or  three  weeks ;  wash  thor- 
oughly with  water;  embed  in  celloidin;  and  stain  with  haematoxylin. 

Lungs. — These  may  be  treated  as  the  trachea;  embed  in  par- 
affin or  celloidin;  and  stain  with  lithium  carmine  or  haematoxylin 
and  eosin. 

Liver. — Fix  with  corrosive  sublimate,  one  per  cent  solution,  twen- 
ty-four hours;  harden  with  alcohol;  embed  in  paraffin:  and  stain 
with  hsematoxvlin  and  eosin. 


MICROSCOPIC  TECHNIQUE.  23 

Kidney. — Fix  and  harden  with  alcohol;  embed  with  paraffin;  and 
stain  with  haematoxylin  and  eosin. 

Ovary. — Fix  and  harden  with  alcohol;  embed  in  paraffin;  and 
stain  with  haematoxylin  and  eosin.  The  Fallopian  tube  may  be 
treated  in  the  same  way. 

Uterus. — Fix  and  harden  with  alcohol;  embed  in  paraffin;  and 
stain  with  haematoxylin  and  eosin. 

Testis. — Fix  with  corrosive  sublimate,  and  harden  with  alcohol; 
embed  in  paraffin ;  and  stain  with  lithium  carmine. 

Eye. — Cut  across  the  eye  so  as  to  partly  divide  it  into  an  anterior 
and  posterior  half;  suspend  in  150  cc.  of  chromic  acid  (0.25  per 
cent)  for  twenty-four  hours;  sever  the  halves  and  renew  the  fluid; 
after  several  days'  wash  in  water,  and  harden  in  alcohol  in  the  dark ; 
embed  in  paraffin ;  and  stain  with  haematoxylin  and  eosin. 

Pancreas. — Fix  with  Flemming's  solution,  twenty-four  hours; 
harden  with  alcohol ;  stain  with  lithium  carmine ;  embedding  may  be 
done  in  paraffin. 

III.  STAINING  METHODS. 

Sections  to  be  stained  may  be  fresh  specimens  or  those  that  have 
been  cut  from  embedded  tissue.  They  may  be  free — that  is,  unat- 
tached to  the  slide,  or  affixed.  The  following  schemes  for  staining 
are  intended  to  be  sufficiently  comprehensive  to  include  all  of  these 
conditions : 

No,   1.  METHOD  FOR  STAINING  FRESH  VEGETABLE 
SECTIONS. 

( 1 )  Apply  section  to  slide  and  add  rosanilin  violet,  one  to  five  min- 
utes. 

(2)  Wash  in  water  to  remove  excess  of  stain. 

(3)  Dry  with  blotting  paper  and  add  glycerine  to  dehydrate. 

(4)  Remove  excess  of  glycerine  and  add  glycerine  again  to  thor- 
oughly dehydrate. 

(5)  Wipe  off  excess  of  glycerine  and  add  xylol  twice. 

(6)  Apply  to  cover-glass  a  drop  or  two  of  xylol-balsam,  and,  hav- 
ing wiped  off  the  excess  of  xylol  from  the  slide,  drop  it  gently  (bal- 
sam down)  upon  the  section.    Then  apply  gentle  pressure  with  dis- 
secting needle  to  spread  out  the  balsam. 


24:  MICROSCOPY. 

(7)  Label  and  keep  in  a  horizontal  position  until  the  balsam  is 
hardened. 

Vegetable  Sections. — To  stain  paraffin  or  celloidin  sections  of 
plant  structures,  the  methods  are  practically  the  same  as  those  given 
below  for  animal  objects. 

Methods  for  Animal  Sections. 

No.  2.  CARMINE  METHOD  FOR  FREE  SECTIONS. 

(1)  Apply  section  to  slide  and  wash  with  thirty-five  per  cent  al- 
cohol. 

(2)  Add  lithium  carmine  sufficient  to  cover  section.,  one  to  five 
minutes. 

(3)  If  necessary,  remove  excess  of  stain  with  acid  alcohol,  five 
to  ten  seconds. 

(4)  Dehydrate  with  increasing  strengths  of  alcohol — thirty-five 
per  cent,  seventy-five  per  cent,  ninety-five  per  cent,  and  absolute. 

(5)  Wipe  off  excess  of  alcohol,  and  when  section  is  partly  dry 
add  creosote  to  clear  up,  five  to  ten  minutes. 

(6)  Wipe  off  excess  of  creosote  and  mount  with  balsam. 

(7)  Center  cover-glass  and  apply  pressure  to  spread  out  the  bal- 
sam. 

(8)  Label  and  lay  aside  in  horizontal  position,  cover-glass  up, 
until  the  balsam  hardens. 

No.  3.  CARMINE  METHOD  WITH  AFFIXED  PARAFFIN 

SECTIONS. 

(1)  Apply  to  the  center  of  the  slide  a  thin  layer  of  collodion- 
clove-oil  mixture. 

(2)  Center  and  attach  the  section,  applying  the  heat  of  a  spirit 
or  Bunsen  flame. 

(3)  Immerse  in  xylol  two  minutes  and  in  turpentine  ten  min- 
utes to  remove  paraffin.     Sections  immersed  in  turpentine  alone 
should  remain  twenty  minutes. 

(4)  Wash  with  alcohol,  decreasing  strengths,  using  thirty-five 
per  cent  alcohol  last. 


MICROSCOPIC  TECHNIQUE.  25 

(5)  Apply  lithium  carmine,  one  to  ten  minutes. 

(6)  Remove  excess  of  stain  with  acid  alcohol. 

(7)  Dehydrate  with  alcohol,  increasing  strengths. 

(8)  Dry  and  clear  up  with  creosote,  five  to  ten  minutes. 

(9)  Wipe  off  excess  of  creosote  and  mount  in  balsam. 

(10)  Center  cover-glass. 

(11)  Label  and  lay  aside  in  horizontal  position  until  balsam 
hardens. 

No.  4.  CARMINE  METHOD  FOR  AFFIXED  CELLOIDIN 
SECTIONS. 

(1)  Center  section  and  affix  with  collodion  mixture. 

(2)  Stain  with  lithium  carmine,  one  to  five  minutes. 

(3)  Remove  excess  of  stain  with  acid  alcohol,  five  to  ten  seconds. 

(4)  Apply  seventy  per  cent  alcohol. 

(5)  Apply  eighty  per  cent  alcohol. 

(6)  Apply  ninety-five  per  cent  alcohol  a  few  seconds. 

(7)  Clear  up  with  creosote. 

(8)  Remove  excess  of  creosote  with  blotting  paper. 

(9)  Mount  with  balsam  and  center  cover-glass. 

(10)  Label  and  lay  aside  in  a  horizontal  position. 

No.  5.  H^IMATOXYLIN  METHOD  FOR  FREE  SECTIONS. 

(1)  With  section  on  slide,  apply  alcohol  of  the  same  strength  as 
staining  solution.  , 

(2)  Stain  with  diluted  ha3matoxylin,  one  to  ten  minutes. 

(3)  Remove  excess  of  stain  with  thirty-five  per  cent  alcohol. 

(4)  Dehydrate  with  alcohols,  increasing  strengths. 

(5)  Clear  up  with  creosote  or  cedar  oil. 

(6)  Center  section  and  apply  balsam  and  cover-glass. 

(7)  Center  cover-glass. 

(8)  Label  and  lay  aside  in  horizontal  position   until  balsam 
hardens. 

No.   6.  KffiMATOXYLIN  METHOD  FOR  AFFIXED  PARAF- 
FIN SECTIONS. 

(1)  Apply  to  slide  a  thin  layer  of  egg-albumen  and  glycerine. 


26  MICROSCOPY. 

(2)  Center  section  and  flatten  it  by  gently  touching  with  end  of 
finger. 

(3)  Apply  heat  of  flame  until  paraffin  melts  (sections  that  have 
been  flattened  upon  water  should  be  heated  much  longer  than 
others). 

(4)  Eemove  paraffin  with  xylol  or  turpentine. 

(5)  Eemove  xylol,  etc.,  with  alcohol,  decreasing  strengths. 

(6)  Stain  with  diluted  haematoxylin,  one  to  ten  minutes. 

(7)  Remove  excess  of  stain  with  thirty-five  per  cent  alcohol. 

(8)  Dehydrate  with  alcohol. 

(9)  Clear  up  with  creosote,  five  to  ten  minutes. 

(10)  Wipe  off  excess  of  creosote  and  mount  with  balsam. 

(11)  Center  cover-glass. 

(12)  Label  and  keep  in  horizontal  position  until  balsam  hardens. 

No.  7.  HJEMATOXYLIN  METHOD  FOE  AFFIXED  CELLOIDIN 

SECTIONS, 

(1)  Center  section  and  affix  with  collodion  mixture. 

(2)  Stain  with  diluted  hgematoxylin,  one  to  ten  minutes. 

(3)  Remove  excess  of  stain  with  acid  alcohol. 

(4)  Apply  seventy  per  cent  alcohol. 

(5)  Apply  eighty  per  cent  alcohol. 

(6)  Apply  ninety-five  per  cent  alcohol  a  few  seconds. 

(7)  Clear  up  with  creosote,  five  to  ten  minutes. 

(8)  Remove  excess  of  creosote  with  blotting  paper. 

(9)  Mount  with  balsam  and  center  cover-glass. 

(10)  Label  and  lay  aside  in  a  horizontal  position  until  balsam 
is  hardened. 

No.  8.  KEMATOXYLIN-EOSIN  METHOD. 

( 1 )  If  desired,  affix  section  to  slide  with  egg-albumen  and  glyc- 
erine or  collodion  and  clove-oil. 

(2)  If  a  paraffin  section,  remove  paraffin  with  xylol   or  turpen- 
tine or  both;  remove  xylol,  etc.,  with  alcohol. 

(3)  Apply  thirty-five  per  cent  alcohol. 

(4)  Stain  with  diluted  hsematoxylin,  one  to  five  minutes. 

(5)  Apply  thirty-five  per  cent  alcohol  to  remove  excess  of  stain. 


MICROSCOPIC  TECHNIQUE.  27 

(6)   Stain  with  alcoholic  eosin  about  five  minutes. 
(?')  Apply  ninety-five  per  cent  alcohol  to  remove  excess  of  stain 
and  dehydrate. 

(8)  Clear  up  with  creosote. 

(9)  Eemove  excess  of  creosote  and  mount  with  balsam. 

(10)  Center  cover-glass  and  label. 

(11)  Lay  aside  in  horizontal  position  until  balsam  hardens. 

Staining  Unicellular  Organisms. 

It  is  often  desirable  to  examine  material  without  staining.  This 
is  accomplished  by  placing  upon  the  glass  slip  a  drop  of  the  ma- 
terial to  be  examined  and  applying  cover-glass.  A  hair  placed  un- 
der the  cover-glass  will  prevent  the  object  from  being  crushed  and 
allow  of  free  motion  in  the  case  of  living  organisms.  Should  it 
be  desired  to  stain  such  preparations,  two  methods  may  be  pursued, 
irrigation  and  cover-glass  staining. 

No.  9.  IRRIGATION  AND  STAINING  MICRO-ORGANISMS. 

(1)  Place  upon  the  slide  a  drop  of  material  to  be  studied. 

(2)  Apply  cover-glass. 

(3)  At  the  edge  of  the  cover-glass,  by  means  of  a  pipette,  place 
a  drop  or  two  of  the  reagent  or  stain. 

(4)  By  means  of  a  triangular  piece  of  blotting  paper  applied  at 
the  opposite  edge  of  the  cover-glass,  absorb  the  moisture  from  the 
preparation,  thus  drawing  under  the  stain. 

No.  10.  COVER-GLASS  PREPARATIONS. 

(1)  Make  a  thin  spread  of  the  substance  to  be  examined  upon  a 
sterilized  cover-glass. 

(2)  Using  a  Cornet  forceps,  dry  the  preparation  by  holding  it 
between  the  fingers  above  a  flame. 

(3)  When  dry  pass  the  cover-glass  three  times  through  a  flame, 
keeping  the  preparation  up. 

(4)  Apply  stain. 

(5)  Wash  in  distilled  water  by  dipping  the  cover-glass  in  the 
water  two  or  three  times. 

(6)  Examine  as  a  water  mount  or,  if  desired,  dry  and  mount 
in  balsam. 


28  MICROSCOPY. 

(7)  Label  and  lay  aside  in  a  horizontal  position  until  balsam 
hardens. 

Note. — The  above  method  may  be  used  for  all  simple  staining. 
Special  methods,  however,  are  often  used,  and  they  will  be  given 
as  required. 

Laboratory  Exercise  No.  3. — Centering  and  labeling.  Upon  the  under 
side  of  your  box-cover  make  an  outline  of  a  slide.  The  pencil  should 
have  a  needle  point.  Connect  opposite  angles  and  place  over  the  inter- 
section of  the  lines  a  cover-glass.  Be  sure  that  the  center  of  the  cover- 
glass  coincides  with  the  center  of  the  diagram.  Now,  carefully  make 
an  outline  of  the  cover-glass.  This  outline  may  be  used  for  centering 
both  the  sections  and  the  cover-glass.  Make  a  drawing  of  this  outline 
on  page  29,  also  a  drawing  of  a  slide  with  labels  and  cover-glass  in  situ. 
Fill  in  the  forms  of  labels  in  second  diagram,  using  the  following  data: 
A  transverse  section  of  the  muscle  of  a  normal  cat  was  stained  with 
lithium  carmine  and  mounted  in  balsam  on  October  1,  1891,  by  John 
Smith. 

Drawings.  For  this  work  the  student  should  provide  himself  with  a 
No.  5  or  a  No.  6  H  Faber  pencil,  a  small  rule  or  triangle  and  a  sheet  of 
thin  blotting  paper.  The  pencil  should  be  kept  sharpened  to  a  needle 
point.  The  majority  of  students  will  say:  I  cannot  draw.  An  honest 
and  faithful  effort  will  often  produce  gratifying  results.  Let  every 
line  mean  something.  Be  scrupulously  neat  in  all  your  work.  Remem- 
ber that  this  work  will  furnish  a  better  exhibit  of  character  and  abil- 
ity than  any  other  task  of  the  laboratory. 

Abbreviations.  The  following  abbreviations  are  employed  in  this 
text: 

Transverse  section — T.  S. 
Longitudinal  section — L.  S. 
Vertical  section — V.  S. 
Low  power — L.  P. 
High    power — H.    P. 
Cubic  centimeter — c.  c. 
Micro-millimeter — /z. 
Millimeter — mm. 
Gram — g. 


MICROSCOPIC  TECHNIQUE. 


Diagram  of  Slide  and  Cover  Glass. 


Diagram  for  centering:  (a)  Slide;  (b)  Cover  Glass;  (c)  Center. 


Labels  in  situ. 


Labeling:  (a)  Label  properly  filled  out  for  reagents,  etc. ;  (b)  Label  descriptive 
of  section. 


30  MICROSCOPY. 


CHAPTEE  III. 
REAGENTS  AND  STAINS. 

In  preparing  the  following  reagents  it  is  well  to  remember  that 
the  weight  of  a  cubic  centimeter  of  water  is  one  gram,  and  that  a 
liter  contains  1,000  cubic  centimeters.  The  formulae  that  are  given 
are  those  most  commonly  used  and  are  briefly  stated : 

NORMAL  FLUIDS. 

Distilled  water.— A  supply  of  distilled  water  should  be  constantly 
at  hand  for  the  preparation  of  the  reagents  and  stains. 

Normal  saline. — This  is  prepared  by  dissolving  one  part,  by 
weight,  of  sodium  chloride  in  150  parts  of  distilled  water. 

MACERATING  FLUIDS, 

Dilute  alcohol. — This  may  be  prepared  by  mixing  one  part  of 
ninety-live  per  cent  alcohol  with  two  parts  of  distilled  water.  Other 
fluids  used  for  this  purpose  are  solutions  of  potassium  bi-chromate, 
two  per  cent,  and  caustic  potash,  twenty-five  per  cent. 

DECALCIFYING  FLUIDS. 

Picric  acid. — Make  a  saturated  aqueous  solution  of  picric  acid. 
This  is  an  excellent  fluid  for  decalcifying  bones,  serving  at  the  same 
time  as  a  staining  reagent.  Crystals  should  be  added  from  time  to 
time,  so  that  some  undissolved  crystals  will  always  remain  in  the 
bottom  of  the  vessel. 

Nitric  acid.— Use  a  ten  per  cent  volumetric  solution  in  water. 
Decalcification  occurs  in  five  to  ten  days. 

FIXING  REAGENTS. 

Absolute  alcohol. — Specimens  should  remain  in  this  reagent  from 
one  to  six  hours,  according  to  size. 

Perenyi's  fluid — 

Nitric  acid  (ten  per  cent) 40  cc. 

Chromic  acid  (0.5  per  cent) 30  cc. 

Alcohol  .  . .  30  cc. 


REAGENTS  AND  STAINS.  31 

A  good  reagent  for  embryos  and  adult  tissues.  Time,  three  to 
twelve  hours ;  dehydrate  with  alcohol. 

Erlicki's  fluid — 

Potassium  bi-chromate   2.5  grams. 

Cupric  sulphate  0.5  grams. 

Water 100  cc. 

A  good  reagent  for  general  use,  for  embryos  and  nervous  tissues. 
Time,  ten  to  fifteen  days ;  dehydrate  with  alcohol. 

Corrosive  sublimate — 

Aqueous  Solution — 

Corrosive  sublimate    1  gram. 

Water    95  cc. 

Alcoholic  Solution — 

Corrosive  sublimate    1  gram. 

Alcohol  (ninety-five  per  cent) ...... .99  cc. 

Used  for  general  purposes,  and  specially  for  alimentary  tract. 
Time,  twenty-four  hours,  hardening  in  alcohol,  to  which  a  few 
crystals  of  iodine  have  been  added. 

Chromic  acid.  — Use  a  0.5  per  cent  solution,  dehydrating  with 
alcohol  in  the  dark. 

Muller's  fluid- 
Potassium  bi-chromate   25  grams. 

Sodium  sulphate   10  grams. 

Water   1,000  cc. 

Pulverize  the  solids  before  adding  water,  and  use  a  piece  of  cam- 
phor in  the  solution  to  prevent  the  formation  of  fungi.  Good  for 
general  use  and  especially  valuable  for  central  nervous  system.  Re- 
quires from  two  to  six  weeks.  Wash  in  water  for  several  days,  and 
dehydrate  with  alcohol. 

Flemming's  fluid — 

Chromic  acid  (one  per  cent  solution) ...  .46  cc. 

Osmic  acid  (two  per  cent  solution) ......  12  cc. 

Glacial  acetic  acid..  .  3  cc. 


32  MICROSCOPY. 

Especially  valuable  for  delicate  tissue.  Time,  two  to  twenty-four 
hours ;  dehydrate  with  alcohol. 

HARDENING  REAGENTS. 

Muller's  fluid,  corrosive  sublimate  solution,  chromic  acid,  and 
others  of  the  reagents  named  above  may  be  used  for  hardening  pur- 
poses. For  general  use,  alcohol  will  be  found  invaluable.  The  tis- 
sue should  be  passed  through  increasing  strengths  of  alcohol,  seven- 
ty per  cent,  eighty  per  cent,  ninety  per  cent,  ninety-five  per  cent, 
and  absolute.  It  should  be  allowed  to  remain  twenty-four  hours  in 
each,  except  that  one  to  six  hours  will  suffice  for  absolute  alcohol. 
Ethyl  alcohol  should  be  used,  or,  in  lieu  of  this,  methyl  alcohol  makes 
a  good  substitute.  To  prepare  absolute  alcohol,  dehydrated  copper 
sulphate  may  be  added  to  the  ethyl  or  methyl  alcohol.  This  will  ab- 
sorb the  water  present. 

EMBEDDING  MEDIA. 

Paraffin  and  celloidin  are  extensively  used  for  embedding  tissue. 
The  process  for  each  has  been  fully  explained  in  the  chapter  on 
"  Microscopic  Technique." 

FIXATIVES. 

Collodion  and  clove  oil  mixture. — Mix  one  part  of  collodion  with 
three  parts  of  clove-oil. 

Egg-albumen  and  glycerine. — Filter  the  whites  of  several  eggs 
and  add  to  the  filtrate  an  equal  volume  of  glycerine.  To  the  mix- 
ture add  a  few  drops  of  carbolic  acid  or  a  small  piece  of  thymol  to 
prevent  putrefaction. 

PARAFFIN  SOLVENTS. 

Xylol,  turpentine,  chloroform,  and  benzole  are  commonly  used 
to  remove  paraffin  from  sections.  A  good  plan  is  to  immerse  the 
slide  containing  the  section  for  a  few  moments  in  xylol,  and  then 
transfer  to  turpentine  for  ten  minutes. 

STAINING  SOLUTIONS. 

The  following  staining  preparations  are  those  most  frequently 
used,  and  will  be  found  adequate  to  the  work  required  by  this  text. 
Should  others  be  needed,  the  formulae  can  be  obtained  from  more 
advanced  works. 


REAGENTS  AND  STAINS.  33 

Hanstem's  rosanilin  violet — 

Methyl  violet 1  gram. 

Fuchsia 1  gram. 

Distilled  water   100  cc. 

Note. — This  is  a  valuable  stain  for  vegetable  sections.  It  should 
be  diluted  for  use  as  desired. 

Lithium  carmine — 

Carmine 2.5  grams. 

Lithium    carbonate    (saturated   solu- 
tion)     100  cc. 

The  carmine  should  be  dissolved  in  cold  solution.  Sections  stain 
rapidly,  and  should  be  decolorized  with  acid  alcohol. 

Dalafield's  haematoxylin — 

1.  Hasmatoxylin 1  gram. 

2.  Absolute  alcohol   6  cc. 

3.  Ammonia  alum  (saturated  sol.)...  100  cc. 

4.  Glycerine 25  cc. 

5.  Methyl  alcohol 25  cc. 

Process.— Dissolve  (1)  in  (2)  ;  add  this  solution  to  (3)  ;  expose 
to  air  and  light  for  a  week;  filter  and  add  (4)  and  (5) ;  allow  it  to 
stand  for  a  long  time  exposed  to  air  and  light. 

Eosin — 

Alcoholic  Eosin  for  Sections. — Make  a  saturated  alcoholic  solu- 
tion. This  is  used  as  a  ground  stain  in  connection  with  haematoxy- 
lin; also  as  a  blood  stain. 

Magenta  for  hlood,  etc. — 

Magenta •. 1  gram. 

Alcohol  (eighty-five  per  cent) 50  cc. 

Water 150  cc. 

Glycerine   200  cc. 

Methylene  blue  for  hlood — 
Make  a  saturated  aqueous  solution. 


34  MICROSCOPY. 

Carter's  carmine  mass  for  injecting — 

Carmine 3  grams. 

Strong  ammonia   6  cc. 

Glacial  acetic  acid  6  cc. 

Coignet's  French  gelatin 7  grams. 

Water 80  cc. 

Process. — "  Place  the  finely  cut  gelatin  in  50  cc.  of  water  for  five 
hours ;  dissolve  the  carmine  in  a  mortar  with  a  little  water,  and  add 
the  ammonia;  let  stand  for  two  hours  and  then  pour  into  a  bottle, 
rinsing  the  mortar  with  the  remainder  of  water;  place  the  gelatin 
and  water  on  a  water-bath  until  the  gelatin  melts.  To  the  carmine 
fluid  add  the  acetic  acid,  a  few  drops  at  a  time  (rinsing  mortar  thor- 
oughly) until  the  fluid  becomes  crimson.  To  the  melted  gelatin  add 
the  crimson  carmine,  little  by  little,  with  continual  stirring.  Keep 
in  a  cool  place  with  surface  covered  with  methylated  spirit.  When 
wanted  for  use,  dissolve  on  water-bath  and  filter  through  flannel 
wrung  out  of  hot  water."  (Fearnley's  Method.) 

CLEARING  AGENTS. 

Those  commonly  used  are  cedar  oil,  creosote,  clove-oil,  xylol,  and 
aniline  oil.  Clove-oil  cannot  be  used  with  celloidin  sections. 

MOUNTING  MEDIA. 

Glycerine  jelly  and  Canada  balsam  are  commonly  used  for  mount- 
ing purposes.  For  the  laboratory  balsam  will  be  found  a  satisfactory 
medium.  Should  xylol  be  used  for  clearing,  the  balsam  should  be 
dissolved  in  xylol.  Chloroform  balsam  may  be  used  in  sections  cleared 
with  chloroform. 

For  the  formulae  of  reagents  and  stains  required  for  work  in  bac- 
teriology and  urinalysis,  the  reader  is  referred  to  the  chapters  in 
which  is  discussed  the  micro-technique  of  these  subjects. 


NORMAL  HISTOLOGY.  35 

PART   II. 

NORMAL  HISTOLOGY. 

This  brief  discussion  of  the  facts  and  principles  of  normal  histol- 
ogy is  applied  chiefly  to  animal  structures,  with  special  reference  to 
the  human  body.  The  animal  body  is  composed  of  organs.  Organs 
are  constituted  of  tissues,  and  tissues  consist  of  cells  and  intercellu- 
lar substances.  The  histologist  has  to  do  chiefly  with  cells.  There- 
lore,  a  thorough  knowledge  of  the  nature,  structure,  and  functions 
of  the  cell  is  necessary  to  an  adequate  comprehension  of  this  sub- 
ject. 

CHAPTEE  IV. 

THE  CELL. 

The  cell  is  a  mass  of  protoplasm  containing  a  nucleus  and  gen- 
erally enclosed  in  a  thin  membrane  called  the  cell-wall.  The  nu 
cleus  is  believed  always  to  be  present,  though  there  are  some  in- 
stances in  which  no  nucleus  has  yet  been  discovered.  The  cell-wall 
is  not  an  essential  part,  and  is  often  absent ;  example,  leucocytes  and 
amcebaB. 

Miller's  Paraffin  Bath.. 


Bausch  &  Lomb  Optical  Co.,  Rochester,  N.  Y. 


NORMAL  HISTOLOGY. 


OUTLINE  OF  THE  CELL. 


Structure 


f  Cell  wall. 

Protoplasm 

Centrospheres. 
Nucleus j 

Vacuoles •! 

/ 

f  C  h  r  o  m  a  t  o  - 


Nucleolus. 
Chromatin. 

Water  vacuoles. 
Food  vacuoles. 

Chloroplasts. 


Cell  contents...  - 


phores  .......  <    Leucoplasts. 

salts.      I  Chromoplasts. 


Volatile  oils. 

Alkaloids. 

Ferments. 


Kinds  of  cells..  |  Sr 

Support. 
Reservoirs  of 
nutriment. 

Cell  multiplica- 


Functions 


-• 

•  -  <   Free  cell  forma- 
tion. 
[  Karyokinesis. 

Asexual  •{ 

'  Normal  fission. 
Budding1. 
Free  cell  forma- 
tion. 

Reproduction  of 
individuals.  .  .  -j 

1   Sexual 

Rejuvenescence 
Spore    forma- 
tion. 

1  Conjugation. 
Parthenogen- 

,,.,,.               (  Anabolism. 
,  Metabolism  .  .  .  .  |  Katabolism. 

esis. 
Fertilization. 

THE  CELL.  37 

STRUCTURE  OF  THE  CELL. 

The  parts  of  a  cell  are  the  cell-wall,  protoplasm,  controspheres, 
nucleus,  and  vacuoles. 

(1)  The    cell- wall. — This  is  the  thin  membrane  inclosing  the 
protoplasm.     With  animals,  the  cell-wall  consists  of  protein;  with 
plants,  it  is  composed  of  cellulose.     Protein  is  a  compound  possess- 
ing the  same  elements  as  starch,  but  with  nitrogen  added.     Cellu- 
lose, C6H10O6,  is  an  isomeric  form  of  starch,  having  the  same  com- 
position, but  differing  from  it  in  being  homogeneous  in  structure, 
not  granular,  and  in  being  less  easily  dissolved  and  less  readily  con- 
verted into  dextrin. 

(2)  Protoplasm,  — This  is  the  living  substance  of  the  cell,  the  or- 
ganic basis  of  life.    It  contains  carbon,  hydrogen,  oxygen,  nitrogen, 
sulphur,  and  sometimes  phosphorus,  iron,  and  other  elements.    No 
chemical  formula  can  be  given  for  its  composition,  but  it  consists 
of  unstable,  constantly  changing  molecules.    When  dead,  its  chem- 
ical nature  is  changed,  and  it  consists  of  protein,  f  carbo-hydrates, 
water,  and  mineral  salts.    Of  these,  protein  alone  possesses  nitrogen. 
Living  protoplasm  is  irritable,  unstable,  deoxidizing ;  has  the  power 
to  eliminate  carbon  di-oxide,  and  can  reproduce  itself,  and,  by  as- 
similation, manufacture  the  innumerable  products  characteristic  of 
plants  and  animals.    The  protoplasm  of  adjacent  cells  is  sometimes 
connected  by  delicate  threads,  which  pass  through  their  walls. 
Protoplasm  is  a  viscid,  transparent  substance  resembling  egg-al- 
bumen.   It  is  never  completely  fluid.    It  is  not  homogeneous,  but 
somewhat  complicated  in  structure.     It  consists  of  two  parts,  the 
cytoplasm  and  the  nucleoplasm.     The  cytoplasm  constitutes  the 
bulk  of  the  protoplasm  in  the  cell.     It  consists  of  an  outer,  dense 
film,  the  ectoplasm,  and  an  inner,  semi-liquid  portion,  the  ento* 
plasm,  containing  a  fibrous  sponge-work  holding  in  its  threads  the 
microsomes,  centrosplieres,  and  nucleus.     Microsomes  are  minute 
spherical  masses  supposed  to  contain  nutrition  for  the  growing  cell, 
but  their  real  functions  are  not  well  understood.    The  neucleoplasm 
enters  into  the  structure  of  the  nucleus  and  nucleolus. 

(3)  The    centrospheres.  --These   are   minute   bodies   associated 
with  the  nucleus  and  scarcely  larger  than  the  microsomes.     Each 
centrosphere  consists  of  an  outer,  hyaline  film  of  cytoplasm,  within 


38  NORMAL  HISTOLOGY. 

which  is  a  fibrous  sponge-work  containing  a  dense  body,  the  centro- 
some.  The  centrosphere  multiplies  by  division,  and  thus  initiates 
the  complicated  processes  by  which  one  cell  develops  into  two. 

(4)  The    nucleus. — This  is  the  larger,  rounded,  dense  portion  of 
protoplasm.    Its  protoplasm  is  styled  nucleoplasm.    Its  structure  is 
similar  to  that  of  the  cytoplasm,  consisting  of  an  outer,  dense  ecto- 
sarc  and  an  inner  sponge- work  containing  one  or  more  nucleoli  and 
the  chromatin,  a  substance  very  susceptible  to  stains.   The  nucleus 
and  centrospheres  constitute  the  centers  of  vitality,  the  sources  of 
growth  and  vital  phenomena. 

(5)  The  valcuole. — This  is  the  cell  cavity  and  contains  a  watery 
fluid  or  food  masses  for  the  nourishment  of  the  cell.     There  may 
be  several  vacuoles  in  a  cell.    In  very  young  cells  there  is  no  vacuole, 
the  protoplasm  filling  the  entire  space.     Old  cells  lose  their  proto- 
plasm and  may  be  empty  or  filled  with  the  products  of  assimilation. 

With  plant  cells  the  cytoplasm  often  forms  a  layer  within  the 
cell-wall,  called  the  primordial-utricle. 

CELL  CONTENTS. 

Besides  the  structures  above  named,  the  cell  contains  the  chromat- 
ophores,  starch,  mineral  salts,  proteids,  fat,  volatile  oils,  alkaloids, 
ferments,  and  pigments. 

(1)  The  chromatophores   are  the  color  bearers.     Among  plants 
there  are  three  kinds — the  chloroplasts,  leucoplasts,  and  chromo- 
plasts.    The  chloroplasts  contain  the  green  coloring  matter,  called 
chlorophyl.    Some  animals  contain  chlorophyl,  as,  for  example,  the 
Green  Euglaena.     Chlorophyl  has  the  power  to  decompose  carbon- 
di-oxide.     Its  chemical  composition  is  unknown.     It  is  soluble  in 
alcohol.     The  chromoplasts  are  the  proteid  products  which  contain 
the  coloring  matter  that  gives  the  color  to  flowers  and  fruits.    The 
leucoplasts,  or  amyloplasts,  are  corpuscles  which  engage  in  the 
manufacture  of  starch  granules.     They  are  found  in  portions  of  a 
plant  removed  from  light. 

(2)  Starch,   C6H10O5,    is   found  in   the   cell   and   is   produced 
within  the  chloroplasts  by  the  union  of  carbon  (obtained  from  C02) 

and  water.     Reaction : 

C02=C+20 

6C  +  5ff20=C6H1005 


THE  CELL.  39 

This  process  is  carried  forward  under  the  influence  of  sunlight. 
Thus  the  plant  stores  up  the  energy  of  the  sunbeam  in  complex 
molecules  to  be  utilized  by  man  and  other  animals. 

Other  carbo-hydrates  often  occurring  in  a  cell  are  dextrin,  glu- 
cose, cane  sugar,  etc. 

(3)  Mineral  salts. — These  often  occur  in  a  cell  in  crystalline 
form.    Crystals  in  plant  cells  are  called  raphides. 

(4)  Proteids. — These  occur  in  plant  cells  as  crystalloids  and 
aleurone  grains.    Crystalloids  are  protoplasmic  bodies,  crystalline  in 
form,  but  not  in  character.    Aleurone  grains  are  proteid  granules 
generally  associated  with  crystalloids. 

(5)  Fat  occurs  in  the  cell  as  globules.    It  contains  the  same  ele- 
ments as  starch,  but  the  hydrogen  and  oxygen  are  not  in  the  pro- 
portion of  water.    It  serves  as  a  reserve  food  supply. 

(6)  The   volatile  oils,    such  as  turpentine,  bergamot,  and  asa- 
fetida,  occur  especially  in  plant  cells,  and  give  to  plants  their  per- 
fumes. 

(7)  The  alkaloids  are  organic  bases  bearing  nitrogen.    The  solid 
alkaloids  contain  oxygen,  whereas  those  that  are  liquid  and  volatile 
do  not.    When  reacting  with  acids  they  form  soluble  salts.     They 
furnish  many  powerful  poisons  and  useful  medicines,  and  are  char- 
acteristic of  plants. 

(8)  The  ferments  are  nitrogenous  compounds  which  have  the 
power  to  bring  about  important  chemical  changes  in  organic  sub- 
stances. 

KINDS  OF  CELLS. 

The  important  kinds  of  plant  cells  are  parenchymatous  and 
prosenchymatous  cells,  traclieids,  and  vessels.  Some  of  the  varieties 
of  animal  cells  are  leucocytes,  epithelial  cells,  cartilage  cells,  bone 
corpuscles,  marrow  cells,  lymphoid  cells,  etc. 

FUNCTIONS  OF  CELLS. 

The  cell  is  the  laboratory  of  the  body  in  which  are  manufactured 
all  those  complex  products  which  enter  into  its  structure.  The 
processes  by  which  these  products  are  elaborated  are  andbolism 
(building  up)  and  Jcatabolism  (breaking  down).  The  two  proc- 


40  NORMAL  HISTOLOGY. 

esses  together  constitute  metabolism,  the  former  being  constructive 
metabolism  and  the  latter  destructive  metabolism. 

The  cell,  by  the  rigidity  of  its  walls  or  its  contents,  gives  support 
to  the  structures  of  the  body. 

The  cell  often  serves  as  a  reservoir  for  the  products  of  assimila- 
tion. 

The  cell  is  the  agent  by  which  new  cells  are  formed  and  by  which 
the  plant  or  animal  is  reproduced. 

The  method  by  which  new  cells  are  formed  is  a  process  of  divi- 
sion. There  are  four  forms  of  cell  division — viz.,  normal  fission, 
budding,  free  cell  formation,  and  karyokinesis. 

Normal  fission  is  the  simple  division  of  a  cell  in  which  the  proto- 
plasm divides  and  a  partition  is  formed  between  the  two  halves. 
Sometimes  it  takes  place  by  a  constriction  of  the  cell-wall. 

Budding. — This  consists  in  the  formation  of  a  rounded  projec- 
tion, or  bud,  on  the  wall  of  the  parent  cell.  This  bud  develops  to 
normal  size,  becomes  cut  off  by  a  partition,  and  generally  separates 
from  the  original  cells ;  example,  yeast. 

Free  cell  formation  takes  place  when  the  protoplasm  of  the  cell 
separates  into  one  or  more  distinct  masses,  each  mass  forming  for 
itself  a  cell-wall.  The  new  cells  are  finally  set  free  by  the  bursting 
of  the  wall  of  the  parent  cell. 

Karyokinesis. — This  is  a  form  of  fission  in  which  the  cell  under- 
goes a  cycle  of  changes,  eventually  producing  two  cells  from  one.  It 
is  more  common  among  animals  than  plants. 

For  the  study  of  karyokinesis  the  growing-  tips  of  onions  and  the 
larvae  of  salamanders  may  be  used.  The  cells  may  be  fixed  with  Flem- 
ming's  solution  or  chromic  acid.  Stain  by  the  usual  methods. 

The  different  stages  through  which  the  cell  passes  in  karyoki- 
nesis are :  "Resting  nucleus,  the  skein,  the  rosette,  the  aster,  the  di- 
aster,  daughter  rosettes,  daughter  skeins,  and  daughter  nuclei. 

REPRODUCTION. 

Plants  and  animals  reproduce  asexually  and  sexually. 

(1)  Asexual  reproduction.  — This  method  is  usually  accom- 
plished by  the  individual  cell,  and  there  are,  therefore,  no  distinc- 
tions of  sex,  the  new  cells  formed  being  exactly  like  the  parent  cell. 


THE  CELL.  41 

Often  spores  are  formed  which  differ  from  the  parent  cell,  but  the 
spores  are  evidently  asexual,  neither  being  produced  by  sexual  or- 
gans nor  presenting  sexual  characteristics. 

The  varieties  of  asexual  reproduction  are  the  following : 
(a)  Normal  fission,  in  which  a  unicellular  animal  simply  divides 
into  two ;  example,  bacteria  and  amoeba?. 

(6)  Budding. — In  this  the  unicellular  organism  produces  a  bud 
wlncl.  eventually  becomes  cut  off,  forming  a  new  individual;  ex- 
ample, yeast. 

(c)  By  endospores.—In  this  method  new  cells  are  formed  with 
in  a  large  cell;  example,  lichens. 

(d)  Rejuvenescence. — By  this  process  the  protoplasm  assumes  a 
rounded  mass,  escapes  from  the  cell-wall,  and  forms  for  itself  a 
new  cell-wall;  examples,  spirogyras  and  diatoms. 

(e)  Spore-reproduction. — The  spore  is  a  modified  cell,  whose 
function  is  to  perpetuate  and  reproduce  the  species.     Spores  are 
generally  formed  in  a  spore  case,  or  sporangium.     The  structural 
elements  of  the  spore  are  the  exosporium,,  or  outer  coat;  endospo- 
rium,  or  inner  coat ;  and  the  protoplasm.  .     . 

(2)  Sexual  reproduction. — This  occurs  when  one  or  two  sexual 
cells  engage  to  reproduce  a  plant  or  animal.  Among  plants  the 
sexual  elements  are  the  spermatazoids  and  the  oospheres.  The 
sexual  elements  of  animals  are  the  spermatazoa  and  the  ova.  The 
varieties  of  sexual  reproduction  are  conjugation,  parthenogenesis, 
and  fertilization. 

(a)  Conjugation. — This  consists  in  the  union  of  two  like  cells. 
In  some  cases  the  protoplasm  of  one  cell  is  discharged  into  that  of 
another,  the  resulting  cell  being  called  a  zygospore,  or  auxospore; 
example,  Spirogyra.  It  may  occur,  also,  by  the  union  of  the  proto- 
plasm of  two  distinct  cells  which  have  previously  discarded  their 
cell-walls.  In  this  method  the  cells  are  structurally  the  same,  but 
as  the  process  is  analagous  to  that  of  the  sexual  method — that  is, 
cytoplasm  fusing  with  cytoplasm,  and  nucleus  with  nucleus,  it  is 
considered  by  the  best  authorities  as  sexual  in  character ;  examples, 
diatoms  and  animalcules. 

(#)  Parthenogenesis.  —  This  occurs  when  one  sex  alone  pro- 
duces a  new  individual.  A  single  sexual  cell  may  be  concerned  or 


42  NORMAL  HISTOLOGY. 

two  cells  of  the  same  sex.  It  is  illustrated  among  aphides  and  cer- 
tain of  the  humbler  lepidoptera. 

(c)  Fertilization. — This  occurs  when  two  sexual  cells  unite  to 
produce  a  new  individual.  It  is  a  process  common  to  higher  plants 
and  animals. 

It  is  evident,  therefore,  that  each  individual  plant  or  animal  has 
its  origin  in  a  single  cell,  and  that  its  organism  is  developed  by  a 
process  of  cell-multiplication.  For  example,  by  the  fusion  of  the 
sexual  elements  the  primordial  cell  of  the  animal  body  is  formed. 
This  cell  divides  by  a  process  of  karyokinesis  and  forms  two  cells. 
Each  of  these  divides,  similarly,  forming  four  cells;  the  four  like- 
wise produce  eight ;  and  the  eight  produce  sixteen.  This  gives  what 
is  called  the  morula,  or  mulberry  stage.  By  rearrangement  of  these 
cells  in  the  form  of  a  pouch  there  is  formed  the  gastrula,  the  cells 
disposing  themselves  in  two  layers.  From  these  layers  is  produced 
a  middle  layer,  thus  forming  the  blastoderm,  consisting  of  three 
distinct  layers, — epiblast  mesoblast,  and  hypoblast.  From  these 
layers,  by  cell-multiplication,  growth  and  differentiation,  all  the 
structures  of  the  body  are  produced. 

Laboratory  exercise  No.  4.. — The  structure  of  a  cell.  Peel  from  the 
outer  surface  of  a  scale  of  an  onion  bulb  a  piece  of  the  epidermis.  Ap- 
ply to  a  slide  and  stain  for  a  few  moments  with  rosanilin  violet.  Wash 
with  water,  apply  cover-glass,  and  examine.  Observe  first  the  form  of 
the  cells  and  their  relative  positions,  then  the  structure  of  each  cell. 
Make  out  the  cell-wall,  the  nucleus  with  its  nucleolus,  and  the  gran- 
ular protoplasm  surrounding  it.  Do  you  observe  any  vacuoles?  Make 
a  drawing  of  several  cells,  exhibiting  the  structures  above  named. 

Laboratory  exercise  No.  5. — To  demonstrate  protoplasm  and  cellulose. 
Make  a  preparation  similar  to  the  above  and  apply  a  drop  of  iodine 
solution.  Examine.  The  protoplasm  will  be  stained  brown,  but  the 
cell-wall  is  not  stained.  Now  remove  cover-glass  and  apply  a  small 
drop  of  sulphuric  acid.  This  changes  the  cellulose  into  soluble  dex- 
trin, which  is  attacked  by  the  iodine  and  turned  blue  or  black.  This 
is  the  iodine  test  for  starch.  Look  for  crystals  of  iodine  and  for  the 
Brownian  movement  among  the  molecular  particles. 

THE  BROWNIAN  MOVEMENT. 

This  is  a  molecular  movement  purely  physical  in  character.  It 
occurs  amoiur  bacteria  and  may  be  mistaken  for  independent  mo- 
tion due  to  vitality. 


THE  CELL.  43 

A  STUDY  OF  CELLS. 

In  the  following  studies  it  is  designed  to  illustrate  the  different 
forms  of  cells  and  the  methods  of  cell-multiplication.  Types  are 
presented  which  are  believed  to  have  a  special  bearing  on  the  work 
of  the  histologist.  Yeast,  Protococcus,  and  Spirogyra  have  been 
selected  to  illustrate  plants,  and  the  Amoeba,  Green  Euglaena,  and 
Slipper  Animalcule,  to  illustrate  animals. 

STUDY  OF  THE  YEAST  PLANT. 

The  Yeast  Plant  is  a  unicellular,  chlorophylless  saprophyte,  which 
reproduces  by  budding  and  ascospores. 
Classification: 

Kingdom — Vegetable. 

Series — Cryptogamia. 

Sub-kingdom — Thallophyta. 
Class — Fungi. 

Sub-class — Ascomycetes. 

Life  History  and  Morphology. — The  Yeast  Plant,  Saccharomyces 
cervisice,  is  the  common  species  used  by  brewers  and  bakers.  It  con- 
sists of  cells,  round  or  oval  in  outline.  Each  plant,  or  cell,  is  called 
a  torula;  when  the  cell  produces  spores  the  term  gonidia,  or  asco- 
spores, is  applied  to  them,  while  the  term  ascus  is  applied  to  the 
cell.  The  cell-wall  is  transparent  and  composed  of  cellulose.  The 
protoplasm  contains  one  or  more  clear  spots  (vacuoles),  and  is  be- 
lieved to  contain  a  nucleus.  Multiplication  occurs  by  budding.  A 
spherical  projection,  or  papilla,  is  produced  on  the  wall  of  the  parent 
cell,  which  forms  for  itself  a  cell-wall,  and,  eventually,  by  a  parti- 
tion, becomes  separated  and  assumes  an  independent  existence.  Be- 
fore separation  occurs,  however,  owing  to  rapid  growth,  the  daugh- 
ter cells  often  throw  out  buds,  thus  forming  a  colony  or  chain.  Ee- 
production  also  occurs  by  the  formation  of  endospores.  The  proto- 
plasm of  the  parent  cell  divides  into  four  masses,  each  of  which 
forms  a  new  cell-wall.  These  are  called  ascospores  and  have  the 
power  to  perpetuate  the  plant  under  unfavorable  conditions.  By 
the  dissolution  of  the  wall  of  the  parent  cell  the  ascospores  are  set 
free  and,  under  favorable  conditions,  reproduce  the  plant. 

In  size,  the  yeast  plant  ranges  from  T(TVir to  *iW  inc^  *n  diame- 


44  NORMAL  HISTOLOGY. 

ter.     In  form,  the  torula  is  spherical  or  ovoidal.     It  has  the  power 

to  produce  fermentation,  thus  changing  sugar  into  alcohol  and  C02. 

C6H1206=2C2H5OH  +  2C02. 

Some  of  the  sugar  breaks  up  into  glycerine  and  succinic  acid 
Yeast  contains  no  chlorophyl,  and,  therefore,,  has  not  the  power  to  de- 
compose C02.  The  elements  necessary  to  form  its  protoplasm,  cel- 
lulose, fat,  etc.,  are  carbon,  oxygen,  hydrogen,  nitrogen,  sulphur, 
phosphorus,  potassium,  magnesium,  and  calcium.  These  are  ob- 
tained chiefly  from  complex  substances,  which  are  broken  up  by 
its  action,  and  their  elements  appropriated  to  form  the  new  com- 
pounds required  for  its  growth  and  reproduction. 

Saccharomyces  cervisice  is  used  in  making  bread,  the  00^  formed 
permeating  the  dough  and  making  it  spongy.  Several  species  are 
used  in  making  beer  and  other  fermented  liquors,  different  flavors 
being  produced  by  different  species. 

Laboratory  exercise  No.  6. — Teast.  Place  in  a  test  tube,  half  filled 
-with  water,  a  small  portion  of  a  cake  of  Fleischman's  yeast,  and  let 
stand  for  a  few  hours  in  a  warm  place.  Place  a  drop  of  the  liquid  upon 
the  slide;  cover  and  examine  with  H.  P.  Look  for  single  cells;  then  for 
a  large  cell  with  a  small  one  attached;  the  small  cell  is  a  bud.  Find 
a  group  of  cells;  this  is  a  colony.  Look  also  for  a  chain.  Irrigate  with 
magenta,  and  search  for  protoplasm  and  a  nucleus. 

Upon  the  freshly  cut  surface  of  a  potato  sow  some  yeast  cells.  In  a 
day  or  so  examine  some  of  the  growth  and  search  for  ascospores.  They 
will  appear  as  rounded  masses  within  the  larger  cells.  Make  drawings 
to  illustrate  a  single  cell,  a  colony,  a  chain,  buds,  and  ascospores. 

PROTOCOCCTJS. 

Protococcus  is  a  unicellular,  chlorophyl-bearing  plant  which  re- 
produces by  normal  fission  and  by  endospores. 
Classification : 

Kingdom — Vegetable. 
Series — Cryptogamia. 

Sub-kingdom — Thallophy  ta . 
Class — Algaa. 

Sub-class. — Chlorophyceae. 
Order — Protocaccales. 

Family — Protococcaceae. 
Genus — Protococcus. 

Species — Protococcus  vulgaris. 
Protococcus  pluvialis. 
Protococcus  nivalis. 


THE  CELL.  45 

Life  History  and  Morphology. — Protococcus  vulgaris,  Green  Pro- 
tococcus, is  a  spherical  organism  ranging  in  size  from  1-10,000  to 
1-350  of  an  inch  in  diameter.  It  consists  of  a  cell-wall  (cellulose), 
protoplasm,  nucleus,  and  nucleolus.  Within  the  cell  the  protoplasm 
is  in  green-colored  masses  containing  chlorophyl.  These  are  the 
cliromato'phores,  or  ehloroplasts.  Multiplication  takes  place  by  fis- 
sion. The  protoplasm  divides  first;  then  a  partition  is  formed  be- 
tween the  two  portions,  and  the  cells  thus  formed  separate. 
Often,  however,  before  the  new  cells  separate,  one  or  both 
may  again  divide,  thus  forming  groups  of  three  or  four  cells;  these 
also  may  be  subject  to  fission,  so  that  groups  of  six,  eight,  etc.,  may 
occur,  the  number  generally  being  some  multiple  of  two.  There  are 
two  states  of  protococcus:  The  quiescent,  just  described;  and  the 
motile  form,  which  is  ovoidal  in  shape  and  is  provided  with  two 
ftagella  which,  by  their  contraction,  give  to  the  cell  a  whirling  mo- 
tion. This  state  of  protococcus  is  called  a  zoospore.  In  course  of 
time  the  zoospore  loses  its  flagella  and  becomes  a  quiescent  cell. 

Protococcus  pluvialis  is  found  in  the  gutters  of  houses,  and  dif- 
fers from  the  foregoing  in  possessing  a  small  amount  of  red  pig- 
ment. It,  also,  reproduces  by  endospores.  The  protoplasm  of  the 
resting  cell  divides  into  four  portions  or  into  many  portions,  in  the 
former  case  producing  megazoospores,  and  in  the  latter,  microzo- 
ospores.  These  are  set  free  by  the  bursting  of  the  wall  of  the  parent 
cell. 

Protococcus  nivalis  is  the  so-called  red  snow  of  Arctic  regions. 

Habitat. — Protococcus  vulgaris  is  found  on  brick,  rocks,  fences, 
houses,  and  the  bark  of  trees. 

Laboratory  exercise  No.  7.— Protococcus.  From  the  north  side  of  a 
tree  or  fence  obtain  some  bark  or  wood  containing'  a  coating'  of  green 
Protoccecus.  Moisten  and  place  under  a  bell  jar  or  in  a  Petri  dish  for 
twenty-four  hours  in  a  warm  place.  When  the  cells  have  begun  to  vege- 
tate, apply  the  surface  of  a  cover-glass.  Some  of  the  cells  will  adhere. 
Add  a  small  drop  of  water  if  necessary,  and  examine  with  H.  P.  Ob- 
serve the  shape,  color,  and  size  of  the  cells.  Find  a  single  cell;  then 
one  with  a  partition  showing  normal  fission.  Find  also  a  triplet  and 
groups  of  four,  eight,  etc.  Search  now  for  motile  forms.  These  are  the 
zoospores.  Irrigate  your  preparation  with  acetic  acid,  and  discover,  if 
possible,  a  nucleus.  Make  drawings  illustrating  a  single  cell,  doublets, 
triplets,  and  groups  of  four  or  more;  also  zoospores. 


46  NORMAL  HISTOLOGY. 

SPIROGYRA. 

Spirogyra  is  a  unicellular,  chlorophyl-bearing  plant  which  repro- 
duces by  normal  fission  and  by  conjugation. 

Classification : 

Kingdom — Vegetable. 
Series — Cryptogamia. 

Sub-kingdom — Thallophyta. 
Class — Algas. 

Sub-class — Chlorophyceae. 
Order — Conjugatales. 

Family — Zygnemacese. 
Genus — Spirogyra. 

Species — Spirogyra  nitida. 

Spirogyra  maxima. 

Life  History  and  Morphology. — Spirogyra  maxima,  commonly 
called  Brook  Silk,  consists  of  a  cylindrical  cell,  longer  than  broad. 
The  cells,  placed  end  to  end,  are  united  into  long  filaments  by  a 
gelatinous  secretion.  They  contain  chlorophyl  bodies  arranged  in 
spiral  form,  hence  the  generic  name.  These  are  the  cliromato- 
phores,  or  chloroplasts.  A  nucleus  is  always  present,  but  not  easily 
seen.  Fission  occurs  by  the  normal  method  and  may  take  place  in 
any  cell  of  a  filament.  Eeproduction  also  takes  place  by  conjuga- 
tion— i.  e.,  two  adjacent  cells  of  filaments  lying  near,  or  in  contact 
with  each  other,  unite  by  the  protoplasm  of  one  being  discharged  into 
that  of  the  other.  This  is  accomplished  by  tubular  projections  being 
thrown  out  from  each  cell,  which  meet  and  form  a  passageway  be- 
tween the  cells.  In  this  case  the  cells  are  alike  and  distinction  of  sex 
has  not  yet  been  discovered.  The  new  cell  produced  by  the  conju- 
gation is  called  a  zygospore.  The  encysted  zygospore  becomes  em- 
bedded in  the  mud  and  preserves  the  life  of  the  plant  through  the 
winter.  If  develops  into  a  new  plant  by  the  protrusion  of  the  in- 
ner coat  through  the  broken  outer  coat,  when  fission  takes  place,  and 
a  filament  is  produced  by  the  vegetative  process.  By  some,  spirogyra 
is  supposed  to  illustrate  sexual  reproduction,  the  conjugating  cells 
being  the  gametes  and  producing  by  their  union  the  zygospores.  The 
sexual  character  of  the  cells  may  yet  be  proven,  for  there  may  be 


THE  CELL.  47 

sexual  differences  (physiological  at  least)  of  which  we  are  yet  ig- 
norant. The  chromatophores  often  contain  bright  spots,  called 
pyrenoids,  and  are  instrumental  in  producing  starch,  which,  as 
minute  granules,  occurs  surrounding  the  pyrenoids.  The  cell  ex- 
hibits cell-wall,  primordial-utricle,  protoplasm,  nucleus,  chromato- 
phores, starch  grains,  pyrenoids,  and  chlorophyl. 

Habitat. — Spirogyra  may  be  found  in  ponds  and  slow-running 
creeks,  and  is  widely  distributed.  It  is  somewhat  smooth  and  slimy 
to  the  touch. 

Laboratory  exercise  No.  8. — Obtain  from  some  pond  or  brook  a  quan- 
tity of  Sphogyra,  placing  it  in  a  large  jar  with  water.  Examine  with 
H.  P.,  observing  the  filaments  composed  of  cells  attached  end  to  end. 
Make  a  study  of  a  single  cell.  Observe  the  spiral  arrangement  of  the 
chloropiusts.  Use  the  1-12-inch  objective  and  search  for  the  pyrenoids 
and  starch  granules.  Find  cells  in  the  process  of  fission.  This  is  to  be 
observed  where  the  cells  are  much  shorter  than  normal  size.  Irrigate 
with  a  drop  of  acetic  acid,  and  search  for  a  nucleus.  Make  drawings 
to  illustrate  filaments  and  a  single  cell  containing  nucleus,  chloroplasts, 
and  cell-wall. 

A  STUDY  OF  ANIMAL  CELLS. 

AMCEBA. 

The  Amoeba  is  a  unicellular  animal  devoid  of  a  cell-wall,  having 
the  power  to  produce  pseudopodia,  and  reproducing  by  normal  .fis- 
sion. 

Classification: 

Kingdom — Animal. 

Series — Protozoa. 

Sub-kingdom — Protozoa. 
Class — Monera. 

Order — Amoebea. 

Genus — Amoeba. 

Species — Amceba  proteus. 

Life  History  and  Morphology. — The  Amoeba  is  an  animal  which 
appropriates  food  without  a  mouth,  digests  without  a  stoimich, 
breathes  without  lungs,  and  has  sensation  without  a  nervous  sys- 
tem. It  is  simply  a  mass  of  protoplasm  consisting  of  cytoplasm  and 


48  NORMAL  HISTOLOGY. 

nucleoplasm.  The  C3^toplasm  consists  of  two  layers,  the  ectoplasm, 
or  dense,  outer  hyaline  layer,  and  the  endoplasm,  or  inner  layer, 
containing  the  microsomes.  The  nucleoplasm  constitutes  the  nu- 
cleus and  contains  masses  of  chromatin,  which  is  very  susceptible  to 
staining  reagents. 

The  animal  has  the  power  to  throw  out  protrusions,  or  pseudo- 
podia,  from  its  body.  A  bulb  is  formed  on  the  surface  of  the  cyto- 
plasm, and  then  all  the  protoplasm  flows  in  this  direction  until, 
often,  the  whole  animal  has  passed  into  the  pseudopodium.  In  the 
meantime,,  other  pseudopodia  are  produced.  The  movement  exhib- 
ited by  the  leucocytes  of  the  blood  is  similar  to  this  and  is  called  the 
amoeboid  movement.  Food  is  obtained  by  flowing  around  it.  There 
nre  two  kinds  of  vacuoles,  food  vacuoles  and  water  vacuoles.  The 
contractile  vesicle  serves  the  function  of  excretion.  The  Amoeba 
reproduces  by  normal  fission — that  is,  the  nucleus  and  protoplasm 
divide  into  two  masses,  without  undergoing  any  process  of  mitosis. 
There  are  two  stages  of  this  animal,  the  active  stage,  just  described, 
and  the  encysted,  or  quiescent,  state.  When  the  animal  is  placed 
under  unfavorable  conditions  it  contracts  into  a  sphere,  forms  an 
enclosing  tough  membrane,  and  in  this  condition  may  be  wafted  by 
the  air  from  place  to  place.  Under  favorable  conditions  the  proto- 
plasm breaks  through  the  enclosing  wall,  and  the  animal  again  en- 
ters the  active  stage. 

Habitat. — The  Amoeba  may  be  found  in  ponds  or  brooks  upon 
submerged  leaves  and  stems,  or  in  the  ooze  which  collects  at  the 
bottom.  To  obtain  material  for  laboratory  use,  collect  some  grass 
and  leaves  from  the  side  of  a  stream,  also  some  submerged  plants 
and  ooze  from  the  bottom  of  a  pond  or  stream,  and  place  in  glass 
jars  for  five  or  six  weeks.  At  the  end  of  this  period  amoebas  should 
be  obtained  in  numbers. 

Laboratory  exercise  No.  9. — Amccbce.  From  the  infusion,  prepared 
as  directed,  carefully  pick  out  a  submerged  leaf,  and  apply  some 
of  the  ooze  upon  its  surface  to  a  slide.  Cover  and  examine  with 
L.  P.  and  H.  P.  Observe  the  ectoplasm,  endbplasm,  and  nucleus.  Make 
out  the  vacuoles  and  contractile  vesicles.  Observe  the  formation  of 
pseudopodia.  Make  drawing's  to  illustrate  protoplasm,  nucleus,  pseu- 
dopodia, and  encysted  stage. 


THE  CELL.  49 

THE  SLIPPER  ANIMALCULE. 

The  Slipper  Animalcule  may  be  found  in  hay  infusion.  It  is  a 
unicellular  animal,  provided  with  a  cell-wall,  and  reproduces  by 
normal  fission. 

Classification: 

Kingdom — Animal. 
Series — Protozoa. 

Sub-kingdom — Protozoa. 
Class — Infusoria. 
Order — Ciliata. 

Genus — Paramoecium. 

Species — Paramcecium  candalum. 

Life  History  and  Morphology. — The  Slipper  Animalcule  is  a  sin- 
gle  cell  provided  with  cell-wall,  protoplasm,  a  double  nucleus 
(macro-nucleus  and  micro-nucleus),  two  contractile  vesicles,  and 
food  and  water  vacuoles.  It  receives  its  food  through  a  mouth. 
Leading  to  the  mouth  is  an  cesophagus  which  terminates  near  the 
middle  of  the  body  surface  in  a  depression  called  the  vestibule.  This 
depression,  as  well  as  the  whole  surface  of  the  cell,  is  provided  with 
cilia.  The  cilia  are  minute,  hair-like,  protoplasmic  projections 
which  by  their  rapid  motion  enable  the  animal  to  move  from  place 
to  place.  Excretion  is  accomplished  by  means  of  an  anal  spot.  This 
is  not  a  permanent  opening,  but  a  thin  place  in  the  cell-wall  through 
which  the  excretions  are  forced  by  means  of  the  contractile  vesicles. 
Reproduction  occurs  by  normal  fission,  and  is  accomplished  by  the 
division  of  the  nucleus  and  protoplasm  into  two  halves  and  the  con- 
striction of  the  cell-wall. 

Laboratory  exercise  No.  10. — Slipper  Animalcule.  Examine  some  of 
the  scum  which  forms  on  the  surface  of  hay  infusion.  Examine  with 
the  high  power,  and,  having-  found  a  specimen  of  the  animalcule  in  a 
quiet  condition,  observe  the  following  structures:  Cell- wall,  cilia,  vesti- 
bule, oesophagus,  mouth,  protoplasm,  double  nucleus,  food  masses,  the 
water  vacuoles,  and  the  contractile  vesicles.  Make  a  drawing  to  illus- 
trate the  structures  thus  named. 
4 


50  NORMAL  HISTOLOGY. 

GREEN  EUGL^INA, 

Green  Euglsena  is  a  unicellular  animal  which  possesses  chloro- 
phyl,  secures  its  motion  by  means  of  flagella,  and  reproduces  b^ 
normal  fission. 

Classification: 

Kingdom — Animal. 1 

Series — Protozoa. 

Sub-kingdom — Protozoa. 
Class — Infusoria, 

Order — Flagellata. 

Genus — Euglsena. 

Species — Euglcena    viridis. 

Life  History  and  Morphology. — Euglwna  viridis  is  an  interesting 
animal  because  of  the  fact  that  its  cell- wall  is  composed  of  cellulose 
and  because  it  possesses  chlorophyl.  The  cell  is  fusiform  in  shape, 
and  is  provided  with  cell-wall,  mouth,,  flagellum  (extending  from 
an  anterior  depression),  an  eye  spot  of  red  pigment  situated  near 
the  mouth,,  and  protoplasm,  chloroplasts,  and  nucleus.  It  has  a 
rotary  motion.  Fission  takes  places  in  a  longitudinal  direction  in- 
stead o'f  transversely,  as  with  the  Slipper  Animalcule. 

Habitat. — The  Green  Euglsena  may  be  found  in  damp  soil,  in 
sewerage,  and  upon  the  surface  of  stagnant  water. 

Laboratory  exercise  No.  11. — Green  Euglaena.  Obtain  some  Green 
Euglsena,  preferably  from  the  surface  of  water.  Examine  with  the 
high  power.  Make  out  carefully  the  structures  mentioned  above.  Do 
you  find  any  evidences  of  cilia?  In  what  two  respects  does  Euglaena  re- 
semble a  plant?  What  is  your  conclusion  as  to  its  nature?  Drawings. 


VEGETABLE  CELLS. 


Onion  Cell.  B.  Yeast. 


A.  Onion  cell :  (a)  Cell-wall :    (b)  Cytoplasm ;  (c)  Primordial  utricle ;  (d)  Nu- 
cleus; (e)  Nucleolus;  (f)  Vacuoles. 

B.  Yeast  plant:  (a)  Single  cell;  (b)  Cell  wall;  (c)  Protoplasm;  (d)  Buds;  (e) 
Colony ;  (f)  Chain ;  (g)  Ascospores. 

A.  Protococcus.  B.  Spirogyra. 


A.  Protococcus:  (a)  Single  cell;   (b)  Cell  wall;  (c)  Chloroplasts ;  (d)  Cell  di- 
vision; (e)  Groups  of  three,  four,  six,  etc.;  (f)  Zoospores;  (g)  Flagella. 

B.  Spirogyra:   (a)   Single  cell;    (b)  Cell  wall;  (c)  Spiral  of  chloroplasts ;  (d) 
Nucleus;  (e)  Pyrenoids;  (f)  Starch  granules ;  (g)  Cell  division ;  (h)  Conjugation. 

[51] 


ANIMAL  CELLS. 


Amoeba. 


Amoeba:  (a)  Active  stage;  (b)  Cytoplasm;  (c)  Nucleus;  (d)  Pseudopodia ; 
(e)  Food  vacuoles;  (f)  Water  vacuoles;  (g)  Contractile  vesicle ;  (h)  Microsomes; 
(i)  Normal  fission ;  (j)  Encysted  stage. 

A.  Slipper  Animalcule.  B.  Green  Euglsena. 


A.  Slipper  Animalcule:  (a)  Cell-wall;  (b)  Cilia;  (d)  Vestibule;  (e)  CEsophagus; 

(f)  Mouth;  (g)  Protoplasm;  (h)  Macronucleus;  (i)  Micronucleus;  (j)  Food  masses; 

(g)  Vacuoles;  (h)  Contractile  vesicles;  (i)  Normal  fission. 

B.  Green  Euglaena:  (a)  Cell-wall;  (b)  Chloroplasts ;  (c)  Mouth;  (f)  Eye-spot; 
(g)  Flagellum. 

[52] 


NORMAL  HISTOLOGY.  53 


CHAPTEE  Y. 
TISSUES  AND  ORGANS. 

A  tissue  consists  of  intercellular  substance  and  an  aggregation  of 
cells  of  common  origin  which  usually  exhibit  a  common  form,  struc- 
ture, and  function.  The  intercellular  substance  may  be  very  slight  in 
quantity  (merely  a  delicate  layer  of  cement  between  the  cells,  as  in 
epithelial  tissue),  or  it  may  make  up  the  bulk  of  the  tissue,  as  illus- 
trated in  the  calcareous  deposit  of  osseous  tissue.  It  is  deposited  by 
the  cells  and  is  usually  formed  by  their  agency.  In  some  tissues  the 
cells  vary  in  form;  for  example,  in  epithelial  tissue,  the  newly- 
formed  cells  are  almost  spherical  and  are  rich  in  protoplasm,  while 
the  old  cells  are  merely  flattened  scales  devoid  of  protoplasm.  In 
osseous  and  nervous  tissues  the  young  cells  may  be  spherical  or 
oval,  while  the  older  cells  are  provided  with  protoplasmic  processes. 

An  organ  is  a  single  tissue  which  exhibits  a  special  function  or  a 
group  of  tissues  so  associated  as  to  accomplish  some  .definite  pur- 
pose in  the  plant-or  animal  economy.  It  is  often  the  case  that  an 
organ  may  serve  several  purposes;  as,  for  example,  the  tongue,  which 
aids  in  mastication,  deglutition,  and  articulation,  and  is  an  organ  of 
taste  and  secretion.  There  is  usually,  however,  one  function  which 
is  preeminent.  In  the  structure  of  an  organ  it  is  not  the  rule  that 
all  its  tissues  are  derived  from  the  same  source.  The  tissues  of 
the  stomach,  for  example,  are  derived  from  the  epiderm,  mesoderm, 
and  hypoderm. 

As  has  been  suggested  in  the  preceding  chapter,  all  the  organs  and 
tissues  of  the  animal  body  are  derived  from  a  single  cell.  This  cell 
is  produced  by  the  fusion  of  a  sperm  nucleus  with  a  germ  nucleus. 
From  this  primordial  cell,  by  a  process  of  segmentation,  there  is 
produced,  first,  the  morula;  then  the  gastrula,  with  its  two 
layers — epiblast  and  hypoblast.  From  these  layers  is  de- 
rived a  third  layer,  the  mesoblast.  We  now  have  the  blastoderm, 
consisting  of  three  distinct  layers  of  cells — epiblast,  mesoblast,  and 
hypoblast.  From  these  layers  are  produced  the  primitive  layers  of 
the  embryo — epiderm  from  the  epiblast,  mesoderm  from  the  meso- 


54:  TISSUES  AND  ORGANS. 

blast,  and  hypoderm  from  the  hypoblast.  From  these  primitive  tis- 
sues are  derived  all  the  structures  of  the  body. 

From  the  epiderm  are  developed  the  nervous  system,  the  epithe- 
lium, covering  the  surface  of  the  body,  the  enamel,  the  nails,  the 
hair,  the  organs  of  special  sense,  and  all  glands  except  those  which 
open  into  the  alimentary  tract  from  the  oesophagus  downward. 

From  the  mesoderm  are  derived  the  blood,  blood-vessels,  all  the 
connective  tissues  (cartilage,  bones,  tendons,  etc.),  the  muscles,  the 
dentine,  and  cementum. 

From  the  hypoderm  are  developed  the  epithelial  lining  of  the 
alimentary  canal  and  the  glands  opening  into  it. 

Tissues  may  be  classified  into  four  groups :  (1)  Epithelial  tissues, 
(2)  Connective  tissues,  (3)  Muscular  tissues,  (4)  Nervous  tissues. 
The  organs  of  the  body  are  constituted  of  these  tissues.  For  ex- 
ample, the  tongue  consists  of  epithelial,  muscular,  connective,  and 
nervous  tissues.  In  the  following  studies  tissues  and  organs  are 
treated  in  the  order  considered  most  convenient  for  practical  work. 
The  first  structure  to  be  considered  is  the  blood. 

MEMORANDA. 


NORMAL  HISTOLOGY. 


55 


CHAPTER  VI. 

THE  BLOOD. 

The  blood  is  a  tissue  of  mesodermic  origin.  It  consists  of  cells, 
called  corpuscles,  and  an  intercellular  substance — the  plasma,  or 
liquor  sanguinis.  The  following  outline  will  exhibit  its  composi- 
tion as  well  as  its  structural  elements : 


OUTLINE  OF  THE  BLOOD. 


Corpus- 
cles . . 


Colored 


Color-  j 
...1 


Nucleated  and  bi-convex  (amphibia,  etc.). 
Non-nucleated  and  bi-concave  (mammalia). 
(  Platelets. 


f  Lymphocytes. 
T  Polynuclear  elements. 

I  Leucocytes j   Eosinophilous  leucocytes. 

[  Phagocytes. 


Fibrinogen. 


Plasma. 


Serum. 


f  Fibrin-ferment.. 
Serum-globulin. 
Serum-albumin. 


Serosity 


Water. 


.Fibrin. 


Mineral  salts. . . 


NaCl. 

Na2CO3. 

Na3P04. 

Ca3(P04)2. 

Mg3(P04)2. 

Sulphates. 


The  corpuscles  are  the  cellular  elements  of  the  blood.  In  man 
the  red  corpuscles,  being  devoid  of  protoplasm,  are  not  alive,  but 
the  leucocytes  exist  in  the  blood  as  so  many  distinct  amoeboid  ani- 
mals. They  can  produce  pseudopodia,  and  have  the  power  of  re- 
producing themselves  by  normal  fission  and  karyokinesis.  The  red 


56  NORMAL  HISTOLOGY. 

corpuscles  occupy  about  fifty  per  cent  of  the  volume  of  the  blood 
in  man,,  thirty-five  per  cent  in  woman.  The  volume  of  the  white 
corpuscles  is  about  two  per  cent. 

Colored  corpuscles,  — In  the  blood  of  man  these  are  usually 
styled  red  discs ;  as  seen  on  edge,  they  appear  to  bulge  at  the  ex- 
tremities and  have  concave  centers.  They  are  devoid  of  cell-wall, 
and  on  account  of  their  flexibility  are  capable  of  crowding  through 
very  narrow  spaces. 

In  the  fish,  salamander,  reptile,  and.  bird  the  red  corpuscle  is 
nucleated  and  bi-convex.  Among  mammals,  including  man,  it  is 
bi-eoncave  and  non-nucleated.  Under  the  microscope  the  color  ap- 
pears jrellowish.  The  red  corpuscles  are  smooth  and  flexible.  Their 
color  is  due  to  the  Ji&maglobin,  which  is  suspended  in  the  pores  of 
the  stroma,  or  ground  substance,  of  the  corpuscle.  The  haBmaglobin 
contains  iron,  which  has  a  strong  affinity  for  oxygen,  forming  with 
that  element  oxyk&maglobin,  which  gives  to  the  blood  its  bright  red 
tinge.  The  dark  color  of  the  venous  blood  is  due,  therefore,  to 
the  haBmaglobin.  The  chief  function  of  the  red  corpuscles  is  to 
serve  as  a  carrier  of  oxygen.  When  exposed  to  the  air  the  red  discs 
arrange  themselves  in  rows  or  stacks,  which  is  called  the  formation 
of  rouleaux.  Water  will  remove  the  haemaglobin.  Sirup  causes  the 
corpuscles  to  shrivel.  Normal  saline  produces  crenation,  due  to  the 
fact  that  the  salt  has  an  affinity  for  the  stroma  and  produces  con- 
tractions upon  the  surface  by  exosmosis.  The  red  corpuscles  are 
manufactured  in  the  liver,  spleen,  and  red  marrow  of  the  bone.  When 
first  formed  they  are  nucleated,  but  afterwards  lose  their  nuclei  by 
mitosis. 

The  size  of  the  red  disc  in  man  is  ^Vir  of  an  inch,  or  about 
7.5  p.  It  would  require  40,000  of  them  to  cover  the  head  of  a  pin. 
There  are  about  350  colored  discs  to  one  leucocyte. 

Colorless  corpuscles.  — The  white  corpuscles  consist  of  the  pla- 
telets and  leucocytes.  The  platelets  are  colorless  elements,  about 
TTJVfr  °^  an  mc^  m  diameter.  They  are  sometimes  very  abundant. 
In  man  the  leucocytes  are  spherical  in  shape,  nucleated,  and 
larger  than  the  platelets  and  red  disks.  They  are  alive  and  ex- 
hibit the  amoeboid  movement,  throwing  out  pseudopodia,  by  means 
of  which  they  move  from  place  to  place.  There  are  four  impor- 


THE  BLOOD.  57 

tant  varieties.  The  lymphocytes  are  the  mono-nucleur  elements,  and 
may  be  large  or  small,  according  as  the  nucleus  more  or  less  than 
half  fills  up  the  space  of  the  cell.  The  polynucleur  leucocytes  pos- 
sess more  than  one  nucleus,  sometimes  four  or  five  nuclei.  The 
eosinophilous  leucocytes  are  those  which  take  the  eosin  stain.  They 
do  not  act  as  scavengers  in  the  system.  The  phagocytes  comprise  all 
leucocytes  which  are  not  stained  by  eosin,  or  about  seventy-five  per 
cent.  They  serve  as  scavengers  in  the  body,  removing  fat  and  for- 
eign substances  from  the  blood  and  attacking  and  destroying  ob- 
noxious microbes.  The  leucocytes  also  assist  in  the  process  of  anab- 
olism,  migrating  through  the  stigmata  of  the  capillaries  to  build  up 
worn-out  tissues  and  going  to  the  relief  of  diseased  structures.  Leu- 
cocytes have  no  cell-wall. 

The  plasma  is  the  liquid  part  of  the  blood  and  consists  of  the 
fibrinogen  and  the  serum.  The  fibrinogen  is  a  proteid  compound 
\\hich  under  the  stimulus  of  the  fibrin-ferment  forms  the  fibrin. 
The  fibrin  is  formed  when  the  blood  is  exposed  to  air,  heat,  etc., 
solidifying  in  slender  fibres  which  collect  in  their  meshes  the  cor- 
puscles, forming  a  clot.  This  process  is  known  as  coagulation.  The 
liquid  which  oozes  from  the  clot  is  the  serum.  The  serum  contains 
the  fibrin-ferm.ent,  the  serum-globulin,  the  serum-albumen,  and  the 
serosity.  The  first  three  of  these  are  proteids  and  contain  nutritive 
material  for  the  growing  cells.  The  serosity  consists  of  the  water 
and  the  mineral  salts.  The  mineral  salts  commonly  found  in  the 
blood  are  sodium  carbonate,  sodium  chlorid,  sodium  phosphate,  mag- 
nesium phosphate,  calcium  phosphate,  and  a  small  amount  of  sul- 
phates. 

The  microscopic  study  of  the  blood  is  an  important  aid  in  de- 
termining the  condition  and  relative  number  of  its  structural  ele- 
ments and  the  presence  of  invading  parasites.  The  serum  of  the 
blood  is  believed  to  be  germicidal,  but  under  abnormal  conditions 
it  becomes  infested  with  certain  species  of  bacteria.  A  species  of 
Vermes,  Distoma  Hwmatobium,  and  a  protozoan,  Plasmodium 
malariw,  are  two  important  animal  parasites  which  infest  the  blood. 

Plasmodium  malariae. — This  parasite  is  considered  by  some  au- 
thorities to  be  a  plant;  by  others  it  is  placed  (with  other  organisms) 
in  a  separate  kingdom,  called  Protista.  The  view  here  adopted  (that 


58  NORMAL  HISTOLOGY. 

it  is  an  animal)  is  the  one  generally  accepted.  This  organism  at- 
tacks the  red  corpuscles,  destroying  the  haemaglobin.  It  may  be 
stained  with  methylene-blue,  aqueous  or  alcoholic  solution,  and  can 
be  detected  as  a  minute  body,  irregular  in  shape,  filling  about  one- 
fourth  of  the  corpuscle.  Its  life  history  includes  five  distinct  stages : 
(1)  The  spore;  (2)  the  protoplasmic,  or  fission,  stage;  (3)  the 
amoeboid  form;  (4)  the  plasmodium,  consisting  of  several  amoeboid 
forms  united;  (5)  the  encysted  stage,  containing  a  cell- wall  within 
which  the  cell  contents  break  up  into  spores.  This  cycle  of  changes 
through  which  the  organism  passes  accounts  for  the  fact  that  per- 
sons afflicted  with  malaria  experience  a  recurrence  of  the  symptoms 
at  stated  intervals. 

Laboratory  exercise  No.  12. — Corpuscles.,  rouleaux,  and  fibrils  of 
fibrin.  Clean  a  slide  and  cover-glass.  This  step  should  precede  nearly 
all  the  exercises  that  follow.  Wrap  the  ring  finger  with  a  kerchief 
from  the  base  to  the  first  joint.  Apply  a  few  drops  of  alcohol  to  cleanse 
the  exposed  surface,  and  then,  with  a  lance  or  sterilized  needle,  with  a 
quick  motion  puncture  the  skin  just  above  the  root  of  the  nail.  Wipe 
off  the  first  drop  of  blood,  and  to  the  next  apply  the  surface  of  a  cover- 
glass.  Place  this  upon  a  slide,  blood  down.  Now  examine  with  H.  P., 
observing  first  the  red  corpuscles,  which  will  be  found  to  be  collecting 
by  their  flat  surfaces  into  rows,  called  rouleaux.  Examine  one  of  the 
discs  on  edge,  then  in  profile.  With  fine  adjustment  focus  up  and  down. 
Why  does  the  center  of  the  disc  appear  alternately  dark  and  light? 
Examine  now  the  platelets  and  leucocytes.  They  may  be  found  in  the 
clear  spaces  between  the  red  discs,  and,  as  they  adhere  to  the  glass,  do 
not  float  about  in  the  serum.  Lay  aside  this  preparation  until  the  next 
period  and  examine  for  the  fibrils  of  fibrin,  which  will  appear  as  deli- 
cate threads  beneath  the  cover-glass. 

Crenation  and  Amoeboid  Movement.  Make  a  second  preparation  by 
the  method  above  described.  Add  to  the  blood  a  small  drop  of  normal 
saline.  Examine  and  observe  the  crenated  appearance  of  the  colored 
discs.  This  is  due  to  exosmosis.  Gently  warm  the  slide  and  look  for 
the  amoeboid  movement  of  the  leucocytes.  To  observe  this  may  re- 
quire that  the  slide  be  kept  warm  for  a  considerable  period. 

Acetic  acid  brings  into  view  the  nuclei  of  leucocytes.  Water  removes 
the  ha?maglobin  from  red  corpuscles,  while  sirup  causes  the  disc  to 
shrivel. 

Laboratory  exercise  No.  13. — Preparation  of  a  blood  slide.  Secure  a 
drop  of  blood  by  the  method  described,  and  apply  a  clean  cover-glass. 
To  this  apply  a  second  cover-glass,  and  with  gentle  pressure  spread  out 
the  blood.  Then,  with  a  quick  motion,  keeping  the  cover-glasses  paral- 
lel, draw  them  apart  so  as  to  leave  a  thin  film  of  blood  on  each.  Select 
the  best  preparation,  lay  it  upon  a  piece  of  writing  paper,  blood  up,  and 


THE  BLOOD.  59 

hold  it  over  a  flame,  being  careful  not  to  ignite  the  paper,  until  the  film 
turns  brown.  The  blood  is  now  properly  affixed,  and  may  be  stained 
by  the  following  method: 

No.  XL   Scheme  for  Staining  Blood  Preparations. 

(1)  Make  a  cover-glass  preparation  and  affix  by  the  method  given 
above. 

(2)  Using  Cornet  forceps,  stain  with  alcoholic  or  glycerine  eosin, 
thirty  minutes  to  one  hour. 

(3)  Wash  off  eosin  by  dipping  cover-glass  vertically  into  distilled 
water  one  or  two  times. 

(4)  Apply  Delafield's  haematoxylin  fifteen  minutes. 

(5)  Wash  in  water,  dry  with  gentle  heat,  and  mount  in  balsam. 

(6)  Label  and  study. 

Observe  that  the  colored  discs  are  stained  red  by  the  eosin,  while  the 
nuclei  of  the  leucocytes  are  stained  blue  by  the  haematoxylin.  Find  sev- 
eral lymphocytes  and  compare  the  sizes  of  their  nuclei.  Study  the  poly- 
nuclear  elements.  How  many  nuclei  do  you  find?  Make  drawings  to 
represent  the  red  corpuscles  on  edge  and  in  profile,  rouleaux,  crenation, 
fibrils  of  fibrin,  lymphocytes,  and  polynuclear  elements. 

Laboratory  exercise  No.  14. — Staining  for  Plasmodium  malariae. 

(1)  Make  a  cover  glass  preparation  from  a  malarial  patient  by  the 
usual  method. 

(2)  Stain  with  alcoholic  methylene  blue,  fifteen  minutes. 

(3)  Wash  in  water  and  examine. 

(4)  Dry,  mount  and  label,  if  a  good  specimen. 

Search  for  the  organism  in  the  red  corpuscles,  also  in  the  plasma. 
It  has  no  definite  form,  but  may  be  semi-lunar,  spindle-shaped,  spher- 
ical, etc.  It  can  be  recognized  by  its  color,  the  discs  not  taking  the 
blue  stain. 

Laboratory  exercise  No.  15.— Counting  the  Uood  corpuscles.  Probably 
the  most  satisfactory  device  for  counting  the  corpuscles  is  by  means  of 
the  centrifuge.  Pursue  the  following  method:  Attach  to  the  graduated 
blood  tube  a  piece  of  rubber  tubing.  Having  secured  a  large  drop  of 
blood,  fill  the  graduated  tube  by  gentle  suction,  and  then  place  it  in  the 
ha3matokrit,  making  the  bearings  secure.  Revolve  the  handle  of  the 
centrifuge  seventy-seven  times  in  one  minute.  This  will  give  5,000  rota- 
tions of  the  haematokrit,  resulting  in  the  precipitation  of  the  red  cor- 
puscles to  the  outer  end  of  the  tube,  the  leucocytes  being  arranged  next, 
and  the  plasma  filling  the  other  end.  If  the  red  corpuscles  fill  half  the 
tube,  standing  at  the  graduation  marked  "  fifty,"  it  indicates  that  there 
are  5,000,000  corpuscles  in  a  cubic  millimeter  of  the  blood;  if  it  stands 
at  the  mark  "  thirty-five,"  there  are  3,500,000  in  a  cubic  millimeter.  The 
numbers  given  above  indicate  the  normal  amount  of  corpuscles  for  man 
and  woman  respectively.  Should  there  be  less  than  the  normal  number, 
it  indicates  anaemia.  Should  there  be  the  required  number  of  red  disks, 
but  too  many  leucocytes,  there  is  an  indication  of  leukaemia.  What 
other  method  may  be  employed  for  counting  corpuscles? 


BLOOD. 


Structural  Elements. 


Blood:  (a)  Red  discs  in  profile  showing  dark  and  light  centers;  (b)  Disc  on 
edge;  (c)  Rouleaux;  (d)  Crenation ;  (e)  Platelets;  (f)  Leucocytes;  (g)  Nucleus; 
(h)  Amoeboid  movement;  (i)  Fission;  (j)  Fibrils  of  Fibrin:  (k)  Crystals  of  hae- 
matin. 

A.  Leucocytes.  B.  Plasmodium  malarise. 


A.  Leucocytes :  (a)  Large  lymphocyte ;  (b)  Small  lymphocyte ;  (c)  Polynuclear 
elements. 

B.  Plasmodium  malarias  :  (a)  Corpuscle  ;  (b)  Plasmodium;  (c)  Spores. 

[60] 


NORMAL  HISTOLOGY.  61 


CHAPTER  VII. 

ENDOTHELIUM  AND  EPITHELIAL  TISSUES 

Endothelium,  — This  structure  is  of  mesodermic  origin  and  con- 
sists of  a  single  layer  of  very  thin  polyhedral  cells  united  edge  to 
edge  by  a  cement  substance.  It  lines  surfaces  not  directly  ex- 
posed to  the  external  atmosphere,  such  as  the  surfaces  of  serous 
and  synovia!  membranes,  forming  the  linings  of  the  heart,  blood 
tubes,  and  other  organs. 

EPITHELIUM. 

Epithelium  is  derived  from  the  epiderm  and  hypoderm  of  the 
embryo.  It  consists  of  cells  of  various  shapes,  which  are  united  by 
cement  and  are  devoid  of  blood-vessels.  The  important  functions  of 
epithelium  are  protection,  secretion,  and  elimination.  The  shape 
of  the  cells  depends  upon  the  amount  and  kind  of  pressure  exerted 
upon  them.  As  a  rule,  when  first  formed,  they  are  spherical.  New 
cells  are  produced  by  karyokinesis.  Blood  vessels  being  absent, 
nourishment  takes  place  by  absorption. 

The  following  are  the  important  varieties : 

Squamous. — Simple  and  Stratified. 

Columnar.  — Simple  and  Stratified. 

Ciliated. — Simple  and  Stratified. 

Modified. — Goblet,  Pigmented,  and  Transitional. 

Specialized. — Glandular  and  N euro-epithelium. 

Squamous  epithelium. — This  structure  consists  of  irregular, 
polyhedral,  flattened  cells,  united  edge  to  edge  in  the  form  of  a  pave- 
ment. The  cells,  when  seen  on  edge,  are  found  to  be  somewhat  bi- 
convex. The  nucleus  is  somewhat  eccentric.  Squamous  epithelium 
is  found  wherever  surfaces  are  subjected  to  considerable  friction. 
There  are  two  varieties — viz.,  simple  and  stratified.  Simple 
squamous  epithelium  consists  of  a  single  layer  of  cells  and  is  found 
lining  the  air  cells  of  the  lungs,  the  capsule  of  the  Malpighian  body, 
the  descending  limb  of  Henle's  arch,  parts  of  the  brain-ventricles, 
and  a  few  other  places. 

The  stratified  variety  consists  of  several  layers  and  is  found  cov- 


62  NOKMAL  HISTOLOGY. 

ering  the  skin,  mouth,  tongue,  lower  half  of  pharynx,  oesophagus, 
epiglottis,  upper  part  of  larynx,  pelvis  of  kidney,  ureter,  bladder, 
beginning  and  end  of  male  urethra,  and  the  whole  female  urethra. 

The  deeper  layers  of  this  tissue  have  cells  more  nearly  spherical, 
which  are  often  connected  with  each  other  by  slender  processes. 
These  procesess  give  rise  to  the  so-called  prickle  cells  of  the  deeper 
layers  of  the  epidermis.  The  cells  of  the  outer  layer  become  much 
flattened.,  lose  their  protoplasm,  and  by  constant  friction  are  worn 
away  and  cast  off.  This  process  is  called  desquamation. 

Columnar  epithelium. — This  form  of  epithelial  tissue  is  consti- 
tuted of  cells  which  are  colummar  in  shape  as  seen  from  the  side, 
but  from  above  they  appear  hexagonal.  The  first  layer,  resting 
upon  the  membrana  propria,  consists  of  spherical  cells,  but  those 
of  the  next  layer  are  oval.  Simple  colummar  epithelium  is  found 
lining  the  mucous  membrane  of  the  alimentary  tract  from  the  car- 
diac orifice  downward.  The  stratified  variety  is  found  in  the  ex- 
cretory ducts  of  glands  leading  into  the  alimentary  tract  and  in  a 
portion  of  the  male  urethra.  This  tissue  is  of  hypodermic  origin. 

Ciliated  epithelium, — This  resembles  columnar  epithelium,  but 
the  outermost  layer  of  cells  is  provided  with  cilia.  Cilia  are  delicate 
protoplasmic  projections  which  by  their  motion  produce  outward 
currents  of  mucus  and  other  products.  The  cells  are  nucleated  and 
rest  upon  a  basement  membrane.  Ciliated  epithelium  occurs  in  the 
nasal  cavities,  the  Eustachian  tubes,  larynx,  trachea,  bronchi,  a  por- 
tion of  the  uterus,  Fallopian  tubes,  vasa  efferentia  (partly),  the  ven- 
tricles of  the  brain,  and  the  central  canal  of  the  spinal  cord. 

Modified  epithelium. — This  is  represented  by  modifications  of 
the  types  given  above.  The  important  varieties  are  goblet  cells, 
pigmented  epithelium,  and  transitional  epithelium. 

Goblet  cells  are  modifications  of  columnar  or  ciliated  cells.  Each 
cell  is  generally  isolated  from  others  of  like  character  and  is  formed 
by  the  elaboration  of  mucin  from  the  protoplasm,  which  so  fills  up 
the  cell  as  to  cause  it  to  become  swollen  and  elliptical  in.  shape. 
Eventually  the  cell  bursts,  discharging  its  contents  upon  the  surface 
of  the  membrane.  This  is  one  source  of  mucus,  and  hence  the  term 
mucous  membrane. 

Pigmented  epithelium. — This  is  represented  by  cells  of  the  squa- 


ENDOTHELIUM  AND  EPITHELIAL  TISSUES.  63 

mous  type  which  have  become  impregnated  with  melanin,  a  dark 
pigment  that  gives  coloration  to  the  structure.  The  pigmeiited 
epithelium  of  the  retina  is  the  best  illustration. 

Transitional  epithelium. — This  occurs  in  the  urinary  tract  and  is 
illustrated  by  modifications  of  squamous  and  columnar  cells,  where 
the  one  kind  merges  into  the  other.  It  occurs  in  the  pelvis  of  the 
kidney,  ureter,  bladder,  and  urethra.  The  cells  are  round,  spindle- 
shaped,  cuboidal,  or  pear-shaped,  and  often  exhibit  one  or  more 
slender  processes. 

Specialized  epithelium.  — This  form  of  epithelial  tissue  consists 
of  cells  so  specialized  as  to  engage  in  the  elaboration  of  secretions ; 
or  to  perform  some  special  function.  There  are  two  varieties — 
glandular  epithelium  and  neuro-epithelium. 

Glandular  epithelium. — The  terms  cuboidal  and  secretory  also 
apply  to  this  tissue,  the  former  arising  from  the  general  shape  of 
the  cells,  the  latter  from  their  functional  character.  It  occurs  in 
the  intestinal,  gastric,  and  salivary  glands,  the  pancreas,  and  liver. 

Neuro-epitlielium. — This  comprises  highly  specialized  cells  which 
aid  in  nerve  sensation.  They  are  found  at  the  terminations  of  the 
nerves  of  special  sense.  The  cells  are  generally  elongated  and  con- 
tain an  inner  nuclear  part  and  an  outer  part  directed  toward  the 
periphery,  which  is  often  provided  with  hair-like  processes.  The 
rods  and  cones  of  the  retina  and  the  olfactory  and  taste  cells  are 
illustrations. 

The  following  ten  characteristics  of  epithelial  cells  should  be 
carefully  considered:  (1)  The  cells  are  superficially  disposed;  (2) 
they  are  united  by  cement;  (3)  they  contain  no  blood-ves- 
sel? :  (4)  they  vary  greatly  in  shape ;  (5)  they  perform  various  func- 
tions, those  of  protection  and  secretion  being  the  more  common; 
(Cl)  the  cells  multiply  by  karyokinesis ;  (7)  they  are  nourished  by 
absorption;  (8)  they  have  eccentric  nuclei;  (9)  they  rest  upon  a 
ba?emenl  membrane,  or  membrana  propria;  (10)  the  cells  contain 
mucin,  melanin,  etc.  It  should  be  borne  in  mind  that  all  these  char- 
acteristics are  not  universally  present. 

Laboratory  exercise  No.  16. — Study  of  epithelial  cells.  Collect  upon 
the  end  of  the  tongue  a  quantity  of  saliva  and  apply  the  same  to  the 
center  of  a  slide.  Cover  and  examine  with  high  power.  Observe  the 


64  NORMAL  HISTOLOGY. 

cells,  scarcely  visible,  and  note  the  protoplasm,  nuclei,  and  nucleoli, 
also  the  cell-wall.  View  a  cell  on  edge.  Is  it  perfectly  flat?  Find  a 
group  of  cells  and  notice  how  they  are  joined  together.  Search  for 
small  spherical  bodies.  These  are  the  salivary  corpuscles,  and  are  in 
reality  escaped  lymphoid  cells  from  the  adenoid  tissue  at  the  root  of 
the  tongue. 

Place  upon  the  slide  some  of  the  scrapings  from  the  pharynx  (upper 
part)  of  a  frog.  Examine  with  H.  P.  and  observe  the  elongated  cells 
with  cilia  in  motion.  Ciliated  cells  may  also  be  demonstrated  from 
scrapings  of  the  macerated  trachea  of  a  pig  or  ox. 

Examine  the  scrapings  of  the  stomach  of  some  animal.  Observe  the 
columnar  cells.  Scrape  the  cut  surface  of  a  liver  with  a  scalpel  and 
mix  the  scrapings  with  normal  saline.  Examine  and  search  for  hepatic 
cells,  representing  glandular  epithelium. 

Epithelium  of  a  frog.  Macerate  the  larva  of  a  frog  or  salamander  in 
dilute  alcohol,  cut  the  casts  from,  the  skin  into  small  pieces,  and  apply 
one  of  these  to  a  slide  and  stain  with  haematoxylin,  method  No.  5. 

MEMORANDA. 


EPITHELIAL  TISSUE. 


A.  Squamous  epithelium.  B.  Columnar  epithelium. 


A.  Squamous  epithelium:   (a)  Squamous  cell;  (b)  Cell  -wall;   (c)  Protoplasm; 
(d)  Nucleus;  (e)  Nucleolus;  (f)  Cell  on  edge;  (g)  Group  of  cells;  (h)  Salivary  cor- 
puscle ;  (i)  Epithelium  of  a  frog. 

B.  Columnar  epithelium :  (a)  Columnar  cells  from  stomach  showing  cell  -wall 
and  nucleus— flat  surface ;  (b)  Columnar  cells— end  view. 

A.  Ciliated  epithelium.  B.  Glandular  epithelium. 


A.  Ciliated  cells:  (a)  Cells,  showing  cell- wall  and  nucleus;  (b)  Cilia;  (c)  Gob- 
let ceUs;  (d)  Section  of  stratified  ciliated  epithelium. 

B.  Glandular  epithelium:  (a)  Cuboidal  cells  from  liver;  (b)  Nucleus. 

5  [65] 


NORMAL  HISTOLOGY. 


CHAPTER  VIII. 

CONNECTIVE  TISSUE. 

Connective  tissue  is  derived  from  the  mesoblast  and  consists  of 
cells  and  intercellular  substance.  It  is  found  between  the  skin  and 
mucous  membranes.  It  differs  chiefly  from  epithelial  tissue  in 
having  a  greater  amount  of  intercellular  substance.  Its  functions 
are  to  connect  different  structures  and  furnish  support  to  the  or- 
gans of  the  body.  The  cells  entering  into  it  are  of  two  kinds,  fixed 
and  wandering.  The  fixed  cell  is  a  flattened  plate  with  nucleus, 
protoplasm,  and  enclosing  membrane.  Sometimes  there  are  projec- 
tions of  the  cell-wall  which  give  a  stellate  appearance.  Wandering 
cells  (such  as  leucocytes)  are  those  which  migrate  from  place  to 
place  in  the  tissue. 

There  are  ten  important  kinds  of  connective  tissues — viz.,  white 
fibrous  tissue,  yellow  elastic  tissue,  areolar  tissue,  adipose  tissue, 
mucous  tissue,  retiform  tissue,  basement  membranes,  cartilage,  bone, 
and  dentine. 

I.  WHITE  FIBROUS  TISSUE. 

This  form  is  composed  of  delicate  fibrils,  often  collected  into  bun- 
dles. The  bundles  may  run  parallel  with  each  other  or  interlace, 
forming  a  mesh-work.  This  tissue  is  found  in  tendons,  the  omen- 
turn,  subcutaneous  tissues,  etc.  In  a  tendon  the  fibrils  compose 
parallel  primary  bundles,  and  these  unite  to  form  secondary  bun- 
dles, each  of  which  is  enveloped  in  a  delicate  sheath.  All  are  bound 
together  to  form  the  tendon,  which  is  encased  in  a  tough  sheath  of 
connective  tissue,  septa  from  which  extend  inward,  enclosing  the 
secondary  bundles. 

laboratory  exercise  No.  17. — Tendon.  Embed  a  piece  of  tendon  in 
celloidin.  Stain  sections  with  carmine,  method  No.  2.  Make  out  the  ex- 
ternal sheath  and  the  septa  of  connective  tissue.  Observe  the  branched 
spaces  for  tendon  cells.  Demonstrate,  if  possible,  the  primary  bundles 
and  the  ends  of  the  fibrils.  Label  and  preserve.  Drawing's. 

II.  YELLOW  ELASTIC  TISSUE. 

This  consists  of  highly  refracting  fibres  which  form  a  network 
and  are  often  associated  with  the  preceding  tissue.  The  fibres,  when 


CONNECTIVE  TISSUE.  67 

free  from  their  attachments,  become  bent  or  coiled,  and,  when  boiled, 
yield  elastin,  and  not  gelatin,  as  is  the  case  with  white  fibres.  This 
structure  occurs  in  the  ligamentum  nuchw,  ligamenta  subflava, 
walls  of  bronchioles  and  alveoli  of  lungs,  arteries,  vocal  cords,  and 
in  connective  tissue  generally.  This  and  the  preceding  form  of  con- 
nective tissue  are  intercellular  in  character  and  are,  therefore,  asso- 
ciated with  cells  in  the  formation  of  tissues.  For  the  practical 
study  of  elastic  fibres,,  the  ligamentum  nuchw  of  an  ox  may  be  used. 

III.  AREOLAR  TISSUE. 

Areolar  tissue  is  composed  of  cells  and  an  intercellular  substance 
which  consists  chiefly  of  white  and  elastic  fibers.  It  lines  the  un- 
der surface  of  the  skin,  forms  the  muscle  sheaths,  and  is  found  in  the 
mammary  gland  and  other  structures. 

IV.  ADIPOSE  TISSUE. 

Adipose  tissue  is  almost  wholly  cellular.  The  cells  are  probably 
formed  from  connective  tissue  corpuscles,  in  which  fat  globules  ap- 
pear, increase  in  size,  and  finally  coalesce.  Thus  is  formed  one  large 
globule  of  fat,  which  distends  the  cell-wall,  crowding  the  protoplasm 
and  nucleus  outward.  The  cells  are  well  supplied  with  blood  capil- 
laries. They  are  bound  together  by  areolar  tissue  into  lobules,  and 
the  lobules  into  lobes.  For  practical  study,  a  section  of  the  tongue 
will  be  found  satisfactory.  It  is  widely  distributed,  occurring  al- 
most everywhere  that  connective  tissue  is  found. 

V.  MUCOUS  TISSUE. 

This  occurs  in  the  umbilical  cord  and  comprises  cells  and  a  gel- 
atinous intercellular  substance  called  the  jelly  of  Wharton.  The 
cells  are  stellate  in  form,  and  the  protoplasmic  processes  anasto- 
mose with  each  other,  forming  a  mesh- work  throughout  the  struc- 
ture. This  tissue  contains  but  few  fibrous  elements,  except  as  the 
cord  approaches  full  time. 

Laboratory  exercise  No.  18. — Umbilical  cord.  Embed  pieces  of  a 
three-months'  umbilical  cord  in  celloidin.  Stain  with  haematoxylin, 
method  No.  5.  Observe  (1)  a  thin  layer  of  superficial  cells;  (2)  the 
blood-vessels,  two  arteries  and  one  vein,  surrounded  by  the  mucous 
tissue,  the  jelly  of  Wharton,  or  mucin,  containing-  the  stellate  cells; 
(3)  look  also  for  white  or  elastic  fibres.  In  what  other  structure  is 
mucous  tissue  found? 


68  NORMAL  HISTOLOGY. 

VI.  ADENOID  TISSUE. 

Adenoid  tissue  consists  of  a  network  of  fibrils  holding  in  their 
meshes  lymphoid  cells  and  leucocytes.  The  fibrils  are  supposed  to 
be  derived  from  cell-processes,  which  anastomose  with  each  other. 
The  nuclei  of  the  cells  appear  at  the  intersections  of  the  fibrils.  It 
occurs  in  lymphatic  glands,  tonsils,  solitary  glands,  and  Peyer's 
patches,  many  mucous  membranes,  spleen,  and  thymus  gland. 

VII.  BASEMENT  MEMBRANE,  OR  MEMBRANA  PROPRIA. 

The  basement  membrane,  or  membrana  propria,  consists  of  a 
delicate  homogeneous  membrane,  composed  of  flattened  plates  of 
cellular  origin,  and  occurs  as  a  supporting  base  for  the  epithelial 
cells  which  line  mucous  membranes  and  the  acini  and  ducts  of 
glands. 

VIII.  CARTILAGE. 

Cartilage  is  a  dense  tissue  made  up  of  an  enclosing  sheath,  the 
perichondrium,  a  somewhat  hyaline  matrix,  either  homogeneous  or 
fibrous,  and  cells. 

The  perichondrium  is  the  enclosing  sheath  of  connective  tissue, 
and  consists  of  two  layers,  an  outer  layer  of  dense  fibrous  tissue  and 
an  inner,  looser  layer.  The  terms  fibrous  and  chondrogenetic  apply 
respectively  to  these  layers.  The  latter  is  so  called  because  it  is 
chiefly  engaged  in  the  formation  of  cartilage.  It  contains  cells  ar- 
ranged in  parallel  rows,  which  multiply  by  mitosis. 

The  matrix  is  a  dense,  intercellular  substance  of  a  white,  bluish, 
or  yellowish  color.  It  may  be  homogeneous  or  more  or  less  supplied 
with  white  or  yellow  fibres. 

Embedded  in  the  matrix  are  the  cartilage  cells.  These  cells  are 
usually  oval  in  outline,  but  are  sometimes  flattened  on  one  side,  the 
flattened  surface  being  toward  the  periphery.  They  are  arranged 
in  pairs  and  groups,  and  are  seldom  crowded,  except  toward  the 
perichondrium.  Each  cell  is  enclosed  by  a  capsule.  The  space 
within  the  capsule,  which  is  filled  up  by  the  cell,  is  called  a  lacuna. 
There  are  three  varieties  of  cartilage,  determined  by  the  presence 
or  absence  of  white  and  yellow  fibres.  They  are  hyaline  cartilage, 
elastic  cartilage,  and  fibro-cartilage. 


CONNECTIVE  TISSUE.  69 

(1)  HYALINE  CARTILAGE. 

THis  is  characterized  by  a  bluish- white,  semi-transparent  matrix, 
free  from  fibres  It  occurs  in  costal  cartilages,  the  articular  ends  of 
bone,  the  trachea,  bronchi,  larynx,  the  auditory  meatus,  and  in  the 
early  cartilage  of  the  foetus. 

Laboratory  exercise  No.  19. — Hyaline  cartilage.  Harden  pieces  of 
costal  cartilage,  or  of  the  sternum  of  a  newt,  in  picric  acid;  embed  in 
celloidin;  stain  with  hsematoxylin,  method  No.  5,  or  carmine,  method 
No.  2.  Examine  with  L.  P.  and  note  the  following-  structures:  (1)  The 
perichondrium  with  its  fibrous  and  chondrogenetic  layers;  (2)  the 
matrix,  free  from  fibres,  in  which  are  embedded  the  cells;  (3)  the  cells, 
lying  in  their  lacunaB  with  inclosing  capsule,  and  arranged  in  groups 
of  two  or  more.  Compare  the  form,  size,  and  disposition  of  the  more 
centrally  located  cells  with  those  toward  the  surface.  Do  you  observe 
nucleoli?  Drawings. 

(2)  ELASTIC  CARTILAGE. 

This  form  is  characterized  by  the  presence  of  yellow  elastic  fibres 
in  the  matrix,  They  first  appear  as  minute  granules,  which  arrange 
themselves  in  linear  rows  and,  coalescing,  form  the  fibres.  The 
color  of  the  matrix  is  yellowish.  Elastic  cartilage  occurs-:-  in  the 
epiglottis,  the  external  ear,  the  Eustachian  tube,  etc. 

Laboratory  exercise  No.  20. — Elastic  cartilage.  Harden  portions  of 
the  ear  of  a  pig  in  picric  acid,  embed  in  celloidin,  and  stain  with  hsema- 
toxylin,  method  No.  5.  Observe,  as  in  the  preceding  preparation,  the 
perichondrium,  matrix,  and  cells.  Note  also  the  yellow,  interlacing 
fibres,  which  extend  from  the  matrix  into  the  perichondrium.  Minute 
granules  of  elastin  will  also  be  seen  with  the  high  power.  Make  out 
the  capsule,  lacuna,  and  cell  structure.  Prepare  drawings  to  illustrate 
all  of  these  structures. 

(3)  FIBRO-CARTILAGE. 

Here  we  have  the  same  structures  as  exhibited  in  hyaline  carti- 
lage, but  the  matrix  is  provided  with  many  bundles  of  white  fibres, 
running  in  different  directions  and  interlacing.  It  occurs  In  the 
intervertebral  disks,  sesamoid  bones,  etc. 

Laboratory  exercise  No.  21. — Fil)ro-cartilage.  Decalcify  and  harden 
with  picric  acid  pieces  of  the  vertebral  column  of  a  cat  so  as  to  include 
the  intervertebral  disk,  or  use  the  intervertebral  disk  of  an  ox.  Freeze 
or  embed  in  celloidin.  Stain  with  lithium  carmine,  method  No.  2. 
Examine  and  note  the  numerous  bundles  of  wavy  fibres,  between  which 


TO  NORMAL  HISTOLOGY. 

are  the  cartilage  cells,  each  inclosed  in  a  thick  capsule.     Make  drawings 
of  all  cartilage  structures. 

IX.   BONE. 

Bone  is  a  compact,  hard  form  of  connective  tissue.  It  comprises 
two  varieties — spongy  and  compact.  The  spongy  form  occurs  in  the 
v.'itebra*  and  the  ends  of  the  long  bones.  Compact  bone  is  formed 
from  the  spongy  variety  by  the  deposit  of  lamellae  in  the  intrat  rabec- 
ular  spaces.  It  is  found  chiefly  in  long  bones  between  the  articular 
ends.  A  bone  comprises  three  characteristic  structures — viz.,  the 
periosteum,  the  lone-proper,  and  the  marrow. 

The  periosteum  consists  of  two  layers,  the  fibrous  layer  of  dense 
fibrous  connective  tissue  which,  as  a  protecting  sheath,  covers  the 
outer  surface,  and  the  osteogenetic  layer,  a  somewhat  loose  struc- 
ture, rich  in  cells  and  blood-vessels.  This  layer  is  so  called  because 
it  assists  in  forming  bone.  Its  cells  eventually  become  the  osteo- 
blasts,  which  are  the  bone  builders.  There  are  slender  portions  of 
the  periosteum  which  project  into  the  bone  proper.  They  are  called 
the  perforating  fibers  of  Sharpey.  They  are  fibers  of  the  periosteum 
which  have  failed  to  ossify. 

The  bone-proper  is  composed  of  cartilage  and  the  carbonate  and 
phosphate  of  lime.  Structurally  considered,  it  comprises  the  Haver- 
sian  systems,  the  inter-Haversian  systems,  and  the  fundamental 
lamellce.  A  Haversian  system  comprises  the  Haversian  canal,  the 
lamellw,  lacunae,  canaliculi,  and  the  bone  cells.  The  Haversian 
canal  is  a  minute  channel,  from  20  //  to  100  >j.  in  diameter,  extend- 
ing longitudinally  and  opening  upon  both  the  inner  and  outer  sur- 
face of  the  bone-proper.  It  contains  an  extension  of  the  marrow, 
and  is  rich  in  blood-vessels,  cells,  and  lymphatics. 

The  lamellae  are  plates  of  bone  substance  formed  in  the  spaces 
between  the  lacuna?  and  arranged  concentrically  around  the  canals. 
The  lacunae  are  the  cavities  which  contain  the  bone  cells.  The  cavi- 
ties which  are  excavated  by  and  contain  the  osteoclasts  are  called 
How  ship' s  lacunw.  The  canaliculi  are  the  slender  tubes  which  ra- 
diate from  the  lacuna?  and  serve  as  lymph  channels,  distributing  nu- 
trient fluids  throughout  the  Haversian  system.  They  anastomose 
with  each  other  and  are  connected  with  the  canals.  The  bone  cells 
are  the  corpuscles  within  the  lacunae.  They  send  out  processes  into 


CONNECTIVE  TISSUE.  71 

the  canaliculi.  They  are  derived  from  the  osteoblasts  by  the  in- 
corporation of  the  latter  within  the  bone  matrix.  Besides  the  Ha- 
versian  system  (with  its  lamellae)  just  described,  there  are  the  inter- 
Haversian,  or  interstitial  lamella;,  and  the  fundamental  lamella?. 
The  fundamental  lamella  cover  the  free  surfaces  of  the  bone  ad- 
jacent to  the  periosteum  and  the  marrow.  The  canals  of  these  lamel- 
lae are  styled  Volkman's  canals. 

The  medulla,  or  marrow,  occupies  the  central  cavity.  It  is  de- 
rived from  the  osteogenetic  layer  of  the  periosteum.  It  is  composed 
of  a  connective  tissue  reticulum  filled  with  cells  and  supplied  with 
an  elaborate  system  of  blood-vessels.  The  connective  tissue  cells, 
or  marrow  cells,  in  young  bone,  become  the  osteoblasts;  but,  in  old 
bone,  deteriorate  into  fat  cells.  Primary  marrow  is.  red,  but  in  the 
adult  bone  it  becomes  yellow,  owing  to  the  formation  of  fat.  The 
marrow  also  contains  certain  large  cells  which  are  agents  in  the  de- 
struction of  bone.  They  are  called  giant  cells,  osteoclasts,  or  my- 
eloplaxes.  They  multiply  by  free  cell-formation,  and  are  also  founl 
in  the  osteogenetic  layer  of  the  periosteum.  The  marrow  is  con- 
sidered an  extension  of  this  layer. 

Bone  formation. — Bone  is  formed  by  two  methods — centrally, 
within  the  cartilage.,  and  superficially,  by  the  periosteum.  By  the 
first  method  a  center  of  ossification  is  produced  by  the  transforma- 
tion of  the  cartilage  cells  into  osteoblasts.  By  these  cells  a  cen- 
tral core  of  bone  (or  bone  areas)  is  formed.  At  the  same  time  a 
layer  of  bone  is  formed  beneath  the  periosteum,  and  trabecula?  are 
thrown  out  from  the  osteogenetic  layer,  which  extend  to  the  center 
of  ossification  and  absorb  the  endochondral  bone,  thus  producing  a 
central  cavity  for  the  marrow.  By  means  of  the  osteoblasts  the 
permanent  bone  is  now  produced  between  the  marrow-cavity  and 
the  periosteum.  Spongy  bone  is  constituted  of  periosteum,  a  mesh- 
work  of  trabeculaa,  and  marrow,  rich  in  osteoblasts,  etc.,  filling  up 
thi-  spaces. 

Laboratory  exercise  No.  22. — Bone.  Harden  and  decalcify  pieces  of 
long  bone  in  picric  acid,  freeze  or  embed  in  paraffin,  and  stain  with 
picro-carmine  or  hsematoxylin,  method  No.  5.  Examine  with  L.  P.  and 
H.  P.  Make  a  study  of  the  periosteum,  observing  the  fibrous  layer,  con- 
sisting of  dense  fibrous  tissue,  and  the  osteogenetic  layer,  consisting  of 
a  loose  fibrous  reticulum  rich  in  cells  and  blood  vessels.  Search  for 


72  NORMAL  HISTOLOGY, 

lacunae  in  the  bone  proper  and  note  their  arrangement;  also  find  Haver- 
sian  canals  and  make  out,  if  you  can,  Haversian  systems.  Examine 
the  marrow  and  demonstrate  marrow  cells  and  osteoclasts.  Prepared 
specimens  of  dry  bone  should  be  examined  to  demonstrate  lacunae  and 
canaliculi.  The  bone  of  a  foetus  may  be  prepared  for  the  study  of  bone 
development.  The  preparations  need  not  be  preserved  unless  especially 
good.  What  is  the  average  diameter  of  the  canaliculi?  Drawings. 

X.  DENTINE. 

Dentine  is  one  of  the  connective  tissues,  being  derived  from  the 
mesoderm.  It  is  commonly  known  as  ivory  and  is  found  in  the 
teeth.  It  differs  from  bone  in  composition  and  structure.  Its  inti- 
mate structure  will  be  given  in  the  chapter  on  the  teeth. 

MEMORANDA. 


CONNECTIVE  TISSUES. 


A.  White  Fibrous  Tissue.  B.  Mucous  Tissue. 


A.  Tendon:    (a)  Tendon  sheath;    (b)  Septa;    (c)  Bundles;    (d)  Fibrils;    (e) 
Branched  cell  spaces;  (f)  Longitudinal  section. 

B.  Umbilical  cord:  (a)  Superficial  cells  from  amnion;  (b)  Arteries;  (c)  Vein; 
(d)  Jelly  ofWharton;  (e)  Stellate  cells;  (f)  Connective  tissue  fibres. 

Hyaline  Cartilage. 


Hyaline  cartilage:    (a)  Fibrous  layer  of  perichondrium;    (b)  Chondrogenetic 
layer;  (c)Matrix;  (d)  Capsule;  (e)  Lacuna;  (f)  Cartilage  cell;  (g)  Group  of  cells. 

[73] 


CONNECTIVE  TISSUES. 


A.  Elastic  Cartilage.  B.  Fibro-Cartilage. 


A.  Elastic  Cartilage  (ear):   (a)  Ferichondrium;   (b)  Matrix;   (c)  Capsule;  (d) 
Lacuna  and  cell;  (e)  Interlacing  elastic  fibres. 

B.  Fibre-cartilage:   (a)  Matrix;   (b)  Bundles  of  fibres;   (c)  Capsule;  (d)  Cells 
and  osteoblasts. 

Bone. 


Bone:   A.  Periosteum:   (a)  Fibrous  layer;   (b)  Osteogenetic  layer;   (c)  Cells; 
(d)  Fibres  of  Sharpey. 

B.  Bone  proper:   (e)  Haversian  system:   (f)  Haversian  canal;   (g)  Lamellae; 
(h)  Lacunae;  (i)  Canaliculi;  (j)  Bone  cells;  (k)  In ter-Haversian  systems;  (1)  Fun- 
damental lamellae;  (m)  Howship's  lacunae  and  osteoclasts. 

C.  Marrow:  (n)  Marrow  cells;  (o)  Osteoclasts;  (p)  Osteoblasts. 

[74] 


NORMAL  HISTOLOGY. 


75 


CHAPTER  IX. 

MUSCULAR  TISSUE. 

Muscle  is  a  tissue  derived  from  the  mesoderm.  It  is  composed  of 
cells  and  a  small  amount  of  intercellular  substance,  and  is  endowed 
with  the  property  of  contractility. 

OUTLINE  OF  MUSCULAR  TISSUE. 


1.  Kinds. 


3.  Functions. 


2.  Structure. . 


Smooth — in   all  involuntary  muscle   except  heart  and 

pharynx. 
Striated — in  heart,  O3sophag%us,  and  all  voluntary  muscle. 


'  Smooth 
muscle . .  J 


Form. 
Structure. 


Striated 
muscle. . 


f  Cells 

Bundles. 

Strata. 

f  Epimysium. 
Sheaths . .  <j 

[_  Perimysium. 

Fasciculi,  composed  of  fibres. 

f  Sarcolemma. 

f  Cells <(    Sarcoph 

I 

1  Nuclei. 


Fibers. . . .  \ 


(  Fibrillae. 


S  a  r  c  os - 
tyles . . . 


Discs. 


Dark. 
Lateral. 

Interme- 
diate. 


There  are  two  kinds  of  muscular  tissue — (1)  smooth,  or  vegeta- 
tive; (2)  striated,  or  animal. 

Smooth  muscle  is  associated  with  all  involuntary  muscles  except 
the  heart  and  pharynx,  and  is  found,  therefore,  in  the  digestive  tract, 


76  NORMAL  HISTOLOGY 

the  digestive  glands,  urinary  glands,  generative  organs,  respiratory 
tract,  vascular  system,  lymphatic  glands,  skin,  etc. 

Smooth  muscle  is  composed  of  spindle-shaped  cells,  each  consist- 
ing of  a  cell-wall,  protoplasm,  and  a  centrally-located  nucleus.  The 
cells  overlap  by  their  extremities  and  are  bound  together  into  bun- 
dles, each  bundle  being  surrounded  by  a  membrane  of  areolar  con- 
nective tissue,  called  the  perimysium.  The  bundles  are  disposed  in 
layers,  or  strata,  the  whole  muscle  being  covered  by  the  epimysium, 
a  connective  tissue  sheath. 

Striped  muscle.  — This  is  composed  of  elongated,  somewhat  cylin- 
drical cells,  each  consisting  of  a  cell-wall  (sarcolemma),  protoplasm 
(sarcoplasm),  and  a  superficially  located  nucleus.  These  cells  are  at- 
tached end  to  end,  thus  constituting  a  slender  filament,  which  is  the 
muscle  fibre.  The  fibre,  therefore,  is  encased  by  a  delicate,  closely- 
fitting  membrane,  the  sarcolemma.  It  exhibits  striations,  or  alter- 
nate bands  of  light  and  dark,  called  disks.  The  nucleus  is  to  be 
found  upon  the  surface  of  the  cell  just  beneath  the  sarcolemma. 
Each  fibre  is  composed  of  sarcostyles  and  sarcoplasm.  Bach  sarco- 
style  consists  of  a  group  of  ultimate  fibrillw,  which  are  held  together 
by  the  surrounding  sarcoplasm.  Each  ultimate  fibril  is  believed  to 
consist  of  a  prismatic  body,  a  dot,  and  a  delicate  filament,  the  dot 
dividing  the  filament  midway  between  the  prisms.  This  peculiar 
structure  is  supposed  to  account  for  the  striations  of  the  fibre,  the 
band  of  prisms  giving  rise  to  the  dark  disks,  the  delicate  filaments 
producing  the  light  lateral  disks,  and  the  dots  forming  the  intermi- 
date  disks.  It  will  thus  be  seen  that  a  voluntary  muscle  is  com- 
posed of  bundles,  the  bundles  are  composed  of  fibres,  the  fibres  of 
sarcostyles,  the  sarcostyles  of  fibrillse,  and  the  fibrillse  of  peculr'ar 
structural  elements,  sarcoplasm  filling  up  the  spaces  between  these 
elements.  The  fibrillas  are  the  contractile  elements.  Contraction 
takes  places  in  a  longitudinal  direction,  not  in  every  direction,  as  is 
the  case  with  naked  protoplasm. 

Enclosing  each  fibre  is  a  sheath  of  areolar  connective  tissue,  the 
endomysium.  This  is  not  to  be  confounded  with  the  sarcolemina, 
which  is  a  part  of  the  fibre.  Surrounding  each  fasciculus,  or  bun- 
dle, is  a  larger  sheath,  the  perimysium;  while  the  sheath  enclosing 
the  whole  muscle  is  the  epimysium. 


MUSCULAR  TISSUE. 


77 


The  striated  fibres  of  the  heart  differ  from  the  voluntary  stri- 
ated fibres  in  being  devoid  of  a  sarcolemma  and  in  having  their  nu- 
clei centrally  located. 

Laboratory  exercise  No.  23. — Striated  muscle.  Harden  pieces  of  vol- 
untary muscle  of  salamander  or  cat  in  alcohol,  embed  in  paraffin,  and 
stain  with  carmine,  method  No.  3.  Make  two  sections,  longitudinal  and 
transverse. 

L.S.  Observe  the  fibres  running  parallel  with  each  other.  Using  the 
high  power,  demonstrate  the  stria tions  of  the  fibres — dark,  lateral,  and 
intermediate.  Examine  the  ends  of  the  torn  fibres  and  search  for  the 
ultimate  fibrils.  Try  and  demonstrate  the  sarcolemma.  The  tissue  of 
a  salamander  will  give  the  best  results. 

T.S.  Examine  a  section  of  an  entire  muscle,  if  possible,  and  demon- 
strate the  epimysium,  perimysium,  and  endomysium.  Focus  upon  the 
end  of  a  fibre  and  locate  the  nucleus  near  the  outer  surface.  What  are 
Cohnheim's  areas? 


Incubator. 


Bausch  &  Lomb  Optical  Co.,  Rochester,  N.  Y. 


MUSCULAR  TISSUE. 


Striated  Muscle. 


Striated  muscle:  T.  S.:  (a)Epimysium;  (b)  Pirimysium;  (c)Endomysium;  (d) 
Fasciculus;  (e)  Fibre;  (f)  Nucleus;  (g)  Cohnheim's  area. 

L.  S.:  (h)  Fibre;  (i)  Sarcolemma;  (j)  Dark  disk;  (k)  Lateral  disk;  (1)  Interme- 
diate disk;  (m)  Nucleus;  (n)  Sarcostyle;  (o)  Ultimate  fibril. 

Smooth  Muscle. 


Smooth  Muscle:  (a)  Single  cells;  (b)  Nucleus;  (c)  Group  of  cells;  (d)  Perimy- 
»ium;  (e)  Epimysium. 

[78] 


NORMAL  HISTOLOGY. 


79 


CHAPTER  X. 
NERVOUS  TISSUES  AND  SYSTEMS. 

1.  NERVOUS  TISSUE. 

Nervous  tissue  is  derived  from  the  epiderm  of  the  embryo  and  en- 
ters into  the  structure  of  the  central,  sympathetic  and  terminal  sys- 
tems, and  is,  therefore,  very  widely  distributed.  The  following  out- 
line exhibits  something  of  the  more  common  characteristics  of 
nervous  tissue  : 

OUTLINE  OF  NERVOUS  TISSUE. 


Cells 


Ganglia 


Fibres 


Structure  . . 


Kinds . 


Processes. . . 


Cells. 

Fibres. 

Sheath. 


Medullated. 


Non-medul- 
lated i 


Nucleus. 
Protoplasm. 

Neuroblast. 

Neuron. 

Neuro-dendron. 

Unipolar. 

Bipolar. 

Multipolar. 

First-type. 

Second-type. 

Neuroglia-cell  or  glia-cell. 

Axis  cylinder. 

Collaterals. 

Dendrites. 


'  Structure 


Nerve  endings , 


(  Neurilemma. 
Medullary  sheath. 
Axilemma. 
Axis  cylinder. 
Fibrils. 

Nodes  of  Ranvier. 
Internodes. 
Nerve  corpuscle. 

Central. 
Peripheral. 


Nodes  and  internodes. 

Nerve  corpuscle  and  Neurilemma. 


80  NORMAL  HISTOLOGY. 

Nervous  tissue  is  composed  of  cells,  ganglia,  and  nerve  fibres. 
A  nerve  cell  is  devoid  of  a  cell-wall;  its  nucleus  has  a  prominent 
nucleolus,  and  its  protoplasm  sometimes  contains  yellowish  gran- 
ules of  pigment.  The  cells  are  the  most  abundant  in  nerve  centers — 
the  brain,  spinal  cord,  and  ganglia.  The  primitive  nerve  cells  are 
called  neurollasts,  and  in  the  course  of  their  development,  by  send- 
ing out  certain  processes  known  as  axis  cylinders  and  dendrites,  pro- 
duce the  different  forms  described  as  the  dendron,  neuro-dendron, 
unipolar,  bipolar,  and  multipolar  cells,  and  first-type  and  second- 
type  cells.  An  axis  cylinder  is  a  slender  protoplasmic  growth  from 
the  pointed  end  of  a  neuroblast.  The  dendrites  are  protoplasmic 
growths  which  arise  from  other  parts  of  the  cell.  The  axis  cylinder 
attains  considerable  length,  often  as  much  as  a  meter;  the  dendrites 
are  short  and  slender.  The  axis  cylinder  gives  off  a  few  lateral 
processes  called  collaterals;  the  dendrites  branch  dichotomously, 
forming  a  dense  network.  The  axis  cylinder  functions  as  a  nerve 
fibre;  the  dendrites  possibly  serve  as  a  supporting  framework  for 
the  neuroplasm,  and  are  supposed  to  be  continuous  with  the  ulti- 
mate fibrils.  A  nerve  cell  with  its  axis  cylinder  is  a  neuron;  a  cell 
with  dendrites  and  an  axis  cylinder  bearing  collaterals  is  a  neuro- 
dendron,  Cells  are  named  also  from  the  number  of  processes  they 
bear — unipolar,  one  process ;  bipolar,  two  processes ;  multipolar,  sev- 
eral processes.  A  first-type  cell  is  one  which  has  a  long  axis  cylinder 
that  becomes  a  medullated  nerve  fibre.  A  cell  of  the  second-type  has 
a  short  axis  cylinder  which  divides  and  subdivides.  The  neuroglia- 
cells  are  small  bodies  which  give  off  a  multitude  of  fibrils  forming 
a  supporting  network,  serving  as  connective  tissue  elements,  and 
holding  together  the  delicate  structures  which  enter  into  nerve  cen- 
ters. They  are  called  glia  cells,  and  the  reticulum  produced  by 
them  is  neuroglia. 

Ganglia  are  nerve  centers  consisting  of  groups  of  cells  and  fibres. 
Some  of  the  fibres  which  enter  the  ganglion  terminate  in  its  cells, 
while  others  pass  through  to  more  distant  points.  The  whole  gan- 
glion is  invested  with  a  connective  tissue  sheath,  and  each  fibre  is 
enclosed  with  an  endoneurium,  which  is  continuous  with  the  cap- 
sule with  which  the  fibre  terminates.  The  brain  and  spinal  cord 
may  be  considered  as  groups  of  large  ganglia. 


NERVOUS  TISSUES  AND  SYSTEMS.  81 

Fibres. — A  nerve  fibre  is  derived  from  an  axis  cylinder  of  a  gan- 
glion cell.  A  ganglion  cell  is  a  cell  of  the  first-type,  producing  a 
medullated  fibre.  The  sheath  which  invests  the  whole  fibre  is  the 
neurilemma,  or  primitive  sheath.  It  is  a  thin,  transparent,  tough 
membrane  of  areolar  connective  tissue.  Directly  beneath  the  neuri- 
lemma is  the  medullary  sheath,  which  consists  of  a  semi-fluid,  high- 
ly-refracting substance,  called  myelin.  Beneath  the  medullary 
sheath  and  immediately  surrounding  the  axis  cylinder  is  a  delicate 
and  very  thin  investment,  the  axilemma.  The  axis  cylinder  is  the 
essential  part  of  the  fibre.  It  may  be  naked,  or  covered  with  medullary 
sheath  alone,  or  with  neurilemma  alone,  or  with  both.  The  medul- 
lary sheath  is  absent  in  the  nerves  of  the  sympathetic  system  and 
occasionally  in  those  of  the  cerebro-spinal  system.  The  neurilemma 
is  absent  in  the  fibres  which  traverse  the  brain  and  spinal  cord.  It 
is  also  absent  in  the  fibres  of  the  olfactory  nerves.  At  certain  reg- 
ular intervals,  the  medullated  fibres  lose  their  medullary  sheath,  and 
the  neurilemma  closes  down  upon  the  axis  cylinder.  These  points 
are  called  the  nodes  of  Ranvier.  The  space  between  two  nodes  is 
the  internode.  About  midway  of  the  internode,  just  beneath  the 
neurilemma,  is  the  nerve  corpuscle. 

The  non-meduliated  fibres  occur  in  the  sympathetic  system.  Each 
fibre  consists  of  axis  cylinder  (composed  of  a  bundle  of  fibrils),  the 
neurilemma,  and  an  oval  nucleus  upon  the  surface  of  the  fibre. 

II.  NERVOUS  SYSTEMS. 

There  are  three  important  nervous  systems — central  nervous  sys- 
tem, sympathetic  system,  and  terminal  system. 

CENTRAL  NERVOUS  SYSTEM. 

This  is  sometimes  called  the  cerebro-spinal  system.  It  consists 
of  the  spinal  cord  and  brain.  Each  of  these  is  constituted  of  gan- 
glion cells,  nerve  fibres,  neuroglia,  and  connective  tissue. 

SPINAL  CORD. 

The  spinal  cord,  located  in  the  spinal  column,  consists  of  gray 
and  white  nervous  matter.  The  gray  matter  is  in  the  center  of  the 
cord,  and  the  white  matter  surrounds  it.  The  gray  matter  is  made 


82 


NORMAL  HISTOLOGY. 


up  of  ganglion  cells,  neuroglia,  and  fibres,  while  the  white  matter 
consists  chiefly  of  medullated  fibres  and  connective  tissue. 
OUTLINE  OF  THE  SPINAL  CORD. 


Fissures  . 


White  sub- 
stance. . . 


Gray  sub- 
stance. . , 


Neuroglia. 


Investments. 


Anterior  median  fissure. 
Posterior  median  septum. 
Anterior  lateral  column. 

Posterior  lateral  (  Column  of  Goll. 

column < 

[  Column  of  Burdoch. 

Anterior  gray  commissure. 
Posterior  gray  commissure. 
Central  canal. 


Lateral  columns 


f  Anterior  roots. 
f  Anterior  cornua . .  <  .- 

[  Posterior  roots. 

f  Reticular  pro- 
|       cess. 

Posterior  cornua .  •{  Column  of  Clark. 
Substantia  gel- 
atinosa. 


Lateral  cornua. 


Multipolar 
cells. . . 


Structure 


Motor  cells 


Nucleus  and 
nucleolus. 

Nuclear  mem- 
brane. 

Axis  cylinder. 

Dendrites. 

f  Antero-median 
group. 

j    Postero-lateral 
group. 


Column  cells. 


f  Ependymal  cells. 
[  Deiter's  cells. 

Dura  mater. 

Arachnoid  membrane. 

Pia  mater. 

Septa  from  pia  mater. 


NERVOUS  TISSUES  AND  SYSTEMS.  83 

The  surface  of  the  spinal  cord  comprises  four  areas :  Anterior, 
posterior,  and  two  lateral  areas.  The  cord  is  divided  vertically  into 
two  lateral  halves  by  the  anterior  median  fissure  and  the  posterior 
median  septum.  These  fissures  do  not  extend  through  the  com- 
missures, 

Each  half  of  the  spinal  cord  is  divided  into  the  anterior  column, 
posterior  column,  and  lateral  column.  These  divisions  are  marked 
by  furrows  indicating  the  exit  of  the  anterior  and  posterior  roots  of 
the  spinal  nerves.  In  the  upper  thoracic  and  lower  cervical  regions, 
two  divisions  appear  in  the  posterior  column,  a  median  portion, 
called  the  column  of  Goll,  and  a  lateral  portion,  the  column  of  Bur- 
dock. 

The  white  matter  is  held  together  by  septa  of  connective  tissue 
which  proceed  from  the  pia  mater.  Under  the  microscope  it  appears 
to  be  made  up  of  a  vast  number  of  nerve  fibres,  exhibiting  an  axis 
cylinder,  as  a  central  dot,  surrounded  by  a  lighter  substance,  the 
medullary  sheath. 

The  gray  substance  of  the  spinal  cord  is  centrally  located,  and 
appears  in  the  form  of  the  letter  H — i.  e.,  two  irregular  bands  con- 
nected by  a  bridge.  The  bridge  consists  of  the  anterior  gray  com* 
missure  and  the  posterior  gray  commissure.  Between  the  two  com- 
missures is  the  central  canal.  This  extends  through  the  cord  longi- 
tudinally, and  is  lined  with  ciliated  epithelium.  It  is  about  1mm 
in  diameter.  The  commissures  consist  of  fibres  derived  from  the 
commissure  cells.  The  white  commissure  is  immediately  in  front  of 
the  anterior  gray  commissure.  Each  lateral  column  of  the  gray 
substance  consists  of  three  well-marked  divisions — the  anterior, 
posterior,  and  lateral  cornua.  From  the  anterior  cornua  emerge  the 
anterior  roots,  while  the  posterior  roots  enter  the  posterior  cornua. 
The  reticular  process,  column  of  Clark,  and  the  substantia  gela-* 
tinosa  enter  into  the  structure  of  a  posterior  cornu.  The  reticular 
process  is  a  net-like  mass  of  gray  substance  at  the  base  of  the  cornu. 
The  column  of  Clark  is  on  the  median  side,  near  the  gray  com- 
missure. The  substantia  gelatinosa  covers  the  horn  and  immedi- 
ately surrounds  the  central  canal.  The  substantia  gelatinosa  Neuro- 
landi;  zona  spongiosa,  and  zona  terminalis  are  also  found  in  the 
posterior  cornu. 


84  NORMAL  HISTOLOGY. 

In  its  intimate  structure  the  gray  matter  consists  of  multipolar 
cells,  neuroglia,  and  medullated  fibres.  The  multipolar  cells  are  of 
two  kinds — motor  cells  and  column  cells.  The  motor  cell  has  a 
large  body  with  long  protoplasmic  processes,  the  dendrites,  and  an 
axis  cylinder,  which,  emerging  from  the  anterior  cornu,  becomes  in- 
vested with  a  medullary  sheath,  thus  producing  the  axis  cylinder 
of  a  nerve  fibre.  The  fibres  of  the  anterior  roots  originate  from  the 
motor  cells.  The  column  cells  are  smaller  than  those  of  the  motor 
type  and  have  fewer  dendrites.  The  axis  cylinders  from  these  cells 
largely  make  up  the  white  substance  of  the  cord.  The  axis  cylinders 
of  column  cells  send  out  many  collaterals  which  penetrate  the  gray 
matter.  After  entering  the  white  matter,  each  cylinder  divides  into 
two  stem-fibres,  ascending  and  descending,  which  extend  longitudi- 
nally through  the  cord,  giving  off  many  collaterals,  which  return 
to  the  gray  matter  and  terminate  in  tufts  of  fibrils,  the  stem-fibres 
eventually  terminating  in  the  same  way.  The  axis  cylinders  which 
originate  in  Clark's  column  do  not  divide  when  they^  reach  the  white 
substance,  as  do  those  of  the  column  cells,  but  proceed  upward  to 
the  cerebellum. 

The  supporting  framework  of  the  gray  matter  consists  of  neu- 
roglia, which  is  composed  of  gliq  cells  and  their  processes.  There 
are  two  kinds  of  glia  cells — the  ependymal  cells  and  Deiter's  cells. 
Ependymal  cells  are  of  the  epithelial  type  and  line  the  lumen  of  the 
central  canal.  They  are  provided  with  cilia  and  send  out  processes 
into  the  surrounding  tissues.  Deiter's  cells  are  found  in  the  gray 
matter,  and  afterwards  in  the  white.  They  send  out  delicate  proc- 
esses, which  form  a  supporting  framework  for  the  delicate  nerve 
structures. 

The  investments  of  the  spinal  cord  are  the  dura  mater,  on  the 
outside;  the  arachnoid  membrane,  centrally  located;  and  the  pia 
mater,  immediately  surrounding  the  cord.  From  the  pia  mater, 
septa  of  connective  tissue  extend  inward. 

There  are  thirty-one  pairs  of  nerves  springing  from  the  spinal 
cord.  The  motor  nerves  are  anterior,  while  the  sensory  nerves  are 
posterior.  These  nerves  are  distributed  to  the  muscles,  skin,  a^d 
other  parts  of  the  body,  where  they  are  provided  with  special  ter- 
minations adapted  to  receive  impressions. 


NERVOUS  TISSUES  AND  SYSTEMS.  85 

BRAIN. 

The  brain  comprises  the  medulla  oblongata,  the  cerebellum,  and 
the  cerebrum.  It  is  directly  connected  with  the  spinal  cord,  and, 
thus,  with  the  nerve  structures  of  all  parts  of  the  body.  It  sends 
forth  twelve  pairs  of  cranial  nerves,  which  supply  the  organs  of 
sense,  lungs,  heart,  etc.  It  possesses  two  kinds  of  nervous  mat- 
ter, gray  and  white.  The  arrangement  of  these  substances  is  the  re- 
verse of  that  exhibited  in  the  spinal  cord,  except  that  in  the  me- 
dulla oblongata  the  gray  matter  is  centrally  located.  The  gray  mat- 
ter is  found  in  the  cerebral  cortex,  the  corpora  striata,  optic  thai  ami, 
corpora  quadrigemina,  cerebral  ganglia,  the  lining  of  the  ventrielos, 
and  the  cerebellar  cortex. 

The  whole  brain  is  encased  with  three  characteristic  membranes, 
the  dura  mater  on  the  outside,  next  to  this  the  arachnoid  membrane, 
and  on  the  inside,  immediately  investing  the  brain,  the  pia  mater. 

The  dura  mater  is  a  dense,  elastic,  fibrous  membrane.  It  sends 
three  processes  into  the  brain  for  its  protection  and  support,  and  also 
penetrates  the  skull.  The  arachnoid  membrane  lies  between  the 
dura  and  pia,  and  is  extremely  thin  and  delicate.  Between  the 
arachnoid  and  pia  is  a  space  filled  with  the  cerebro-spinal  fluid.  The 
membrane  is  composed  of  white  fibres  and  elastic  tissue.  The  pia 
mater  consists  of  a  plexus  of  blood  vessels  held  together  by  delicate 
areolar  tissue. 

OUTLINE  OF  THE  BRAIN. 


Medulla  ob- 
longata   


Anterior  median. 
Fissures. . . .  \   Posterior  median. 

Two  lateral  fissures. 

Anterior. 
Surfaces  ..A   Lateral. 


Posterior. 
f  White  matter. 


Substances.  •{ 

[_  Gray  matter. 

f  Cerebellar      f  Molecular  layer. 

n       ,    ,,  cortex  . . .  <   Layer  of  Purkinji's  cells. 

Cerebellum  . .  j  |  Granular  layer. 

I  Medulla,  or 

white  mat-  f  Medullated  fibres, 
ter. 

Connective  tissue. 


86 


NORMAL  HISTOLOGY. 


Cerebral 
cortex 


Cerebrum <j   Medulla. 


Ventricles. 


Brain  invest- 
ments  . 


f  Granular  layer. 

Layer  of  small  pyramidal  cells. 
<{    Layer  of  large  pyramidal  cells. 
I    Layer  of  irregular  cells. 
t  Layer  of  fusiform  cells. 

Medullated  fibres. 
Connective  tissue. 

f  Multipolar  ganglion 
Gray  matter. 


White  matter. 


Medullated  fibres. 
Medullated  fibres. 
Connective  tissue. 


Dura  mater. 
Arachnoid  membrane. 
Pia  mater. 


MEDULLA  OBLONGATA. 

The  structure  of  the  medulla  oblongata  is  virtually  the  same  as 
that  of  the  spinal  cord.  The  chief  difference  consists  in  the  arrange- 
ment of  the  structural  elements. 


CEREBELLUM. 

The  cerebellum  consists  of  the  cerebellar  cortex  and  medulla. 

The  cerebcllar  cortex  comprises  three  layers — the  molecular  layer, 
of  Purkinji's  cells,  and  granular  layer.  The  molecular  layer 
is  composed  of  large  and  small  multipolar  ganglion  cells.  The  small 
cells  are  disposed  toward  the  surface.  The  large  cortical  cells  are  in 
the  deeper  portion  of  the  cortex  and  send  out  protoplasmic  processes 
toward  the  surface.  Purkinji's  cells  are  large,  somewhat  pear- 
shaped  ganglion  cells,  which  send  out  two  large  protoplasmic  proc- 
esses from  one  pole  of  each  cell  into  the  molecular  layer.  The  axis 
cylinder  proceeds  from  the  opposite  pole,  becomes  a  medullated  fibre, 
and  enters  the  white  matter  of  the  cerebellum.  The  granular  layer 
is  the  innermost,  and  is  composed  of  large  and  small  cells  provi-M 
with  large  nuclei.  The  whole  layer  presents  a  rusty  appearance. 
Each  cell  is  provided  with  dendrites  and  a  non-medullated  nerve 
process,  which  extends  into  the  molecular  layer. 


NERVOUS  TISSUES  AND  SYSTEMS.  87 

The  white  matter  consists  of  meduttated  fibres  and  neuroglia. 
There  are  two  kinds  of  neuroglia  cells  in  the  cerebellum:  First, 
small  rounded  cells,  which  occur  in  the  granule  layer  and  send  a 
few  processes  downward  and  many  longer  processes  outward  to  the 
molecular  layer;  second,  stellate  cells,  which  are  found  in  all  the 
layers. 

CEREBKTJM. 

The  cerebrum  comprises  the  cerebral  cortex,  medulla,  and  ventri- 
cles. 

The  cerebral  cortex  is  composed  of  five  layers  which  merge  im- 
perceptibly into  each  other.  They  are : 

( 1 )  Molecular  Layer. — This  is  superficial,  and  is  finely  granular, 
with  an  interlacing  of  medullated  fibres  and  a  reticulum  of  neu- 
roglia.    The  cells  of  Caji  are  found  in  this  layer. 

(2)  Layer  of  Small  Pyramidal  Cells. — This  is  composed  of  gan- 
glion cells  which  are  pyramidal  in  form.     They  send  out  several 
apical  and  lateral  dendrites,  which  penetrate  the  molecular  layer 
and,  by  continuous  division,  produce  a  complicated  network.     The 
axis  cylinder  proceeds  from  the  basal  end  of  the  cell  and,  after  send- 
ing out  a  few  collaterals,  enters  the  medulla. 

(3)  Layer  of  Large  Pyramidal  Cells. — This  differs  from  the  pre- 
ceding in  the  size  of  its  cells.     The  axis  cylinder  process  enters  the 
medulla  to  become  a  medullated  fibre. 

(4)  Layer  of  Irregular  Cells. — This  is  composed  of  cells,  oval  or 
polygonal,  which  are  devoid  of  apical  dendrites.    Each  axis  cylinder 
sends  out  collaterals  and  then  enters  the  medulla  to  become  one  or 
two  nerve  fibres. 

(5)  The  Layer  of  Fusiform  Cells. — This  lies  adjacent  to  the 
medulla  and  is  composed  of  a  few  spindle-shaped  cells  with  ner^e 
fibres  between  them.    The  cells  are  arranged  parallel  with  the  course 
of  the  fibres. 

The  medulla.  — This  comprises  the  white  matter  of  the  cerebrum, 
and  is  composed  of  medullated  fibres  and  connective  tissue  struc- 
tures. 

The  ventricles. — The  gray  matter  of  the  ventricles,  like  that  of 
the  cerebral  cortex,  is  composed  of  multipolar  ganglion  cells,  neu- 


88  NORMAL  HISTOLOGY. 

roglia,  and  medullated  fibres.  The  cells  give  rise  to  axis  cylinders 
which  produce  the  cranial  nerves.  The  white  matter  of  the  ven- 
tricles consists  of  medullated  fibres  and  neuroglia. 

THE  SYMPATHETIC  NERVOUS  SYSTEM. 

The  sympathetic  system  consists  of  a  double  chain  of  ganglia 
(about  twenty-four  pairs)  extending  along  the  anterior  portion  of 
the  spinal  column  and  connected  together  by  intervening  cords, 
three  great  plexuses  (cardiac  in  cervical  region,  epigastric  in  ab- 
dominal region,  and  hypogastric  in  pelvic  region),  smaller  ganglia, 
and  many  non-medullated  nerve  fibres.  The  nerve  fibres  are  of  two 
kinds — communicating  and  distributory.  They  are  non-medullated, 
and  by  some  authorities  are  supposed  to  be  without  a  neurilemma. 

TERMINAL  NERVOUS  SYSTEM. 

The  peculiar  modifications  of  nerve  endings  may  appropriately 
be  considered  as  constituting  a  third  nervous  system,  the  terminal 
system,  often  styled  the  peripheral  system. 

Every  nerve  has  central  and  peripheral  terminations.  The  cen- 
tral ending  is  in  the  cell  with  which  it  originates.  There  are  three 
important  varieties  of  peripheral  endings  for  sensory  nerve  fibres — • 
viz.,  free  nerve  endings,  terminal  corpuscles,  and  neuro-epithelial 
cells. 

1.  Free  nerve  endings  occur  in  the  skin,  mouth,  cornea,  and 
spinal  cord.     By  this  method  the  nerve  fibre  loses  its  neurilemma 
and  medullary  sheath,  and  the  axis  cylinder  breaks  up  into  deli- 
cate fibrils,  which  sometimes  anastomose  with  each  other.     In  the 
skin  the  fibrils  are  confined  to  the  stratum  Malpighii. 

2.  Terminal  corpuscles  occur  in  the  skin.    Stirling  and  Piersol 
give  four  kinds  of  peripheral  corpuscles — (1)  simple  tactile  cells, 
(2)  compound  tactile  cells,  (3)  end  bulbs,  (4)  touch  corpuscles. 

Simple  tactile  cells  occur  in  the  stratum  Malpighii.  The  fibre 
breaks  up  into  fibrils  by  the  usual  method,  but  each  fibril  terminates 
in  a  tactile  disk,  above  which  lies  the  tactile  cell. 

In  compound  tactile  cells,  the  tactile  disk  forming  the  termination 
of  the  axis  cylinder  lies  between  two  tactile  cells. 

End  bulbs  occur  in  mucous  membranes,  the  cutis,  and  other 


NERVOUS  TISSUES  ANE  SYSTEMS.  89 

places.  The  bulbs  vary  in  shape,  round  to  cylindrical,  and  consist 
of  a  fibrous  capsule  and  a  central  core  in  which  terminates  an  axis 
cylinder.  The  Pacinian  corpuscle,  which  occurs  in  the  subcutaneous 
tissue  of  certain  localities,  is  a  variety  of  the  same  and  is  peculiar  in 
exhibiting  many  concentric  fibrous  Iamina3. 

Touch,  corpuscles  occur  in  the  papillae  of  the  skin.  The  nerve 
fibre  as  it  enters  the  corpuscle  breaks  up  into  fibrils,  which  form  a 
coil,  giving  a  striated  appearance. 

3.  Nemo-epithelium. — This  occurs  in  the  perceptive  organs  and 
consists  of  highly  specialized  cells,  such  as  the  rod  and  cone  cells  of 
the  retina,  and  olfactory  and  gustatory  cells.  These  cells  receive 
the  stimuli  from  external  sources,  the  nerve-fibres  conveying  them 
onward  to  the.  nerve  centers. 

Laboratory  exercise  No.  24. — The  spinal  cord.  Harden  pieces  of  the 
spinal  cord  of  a  cat  in  Muller's  fluid,  embed  in  paraffin,  and  stain  with 
hsematoxylin  and  eosin,  method  No.  8.  Examine  first  with  L.  P.,  then 
with  H.  P.  Study  the  structure  of  the  inclosing  membranes.  Observe 
the  septa  of  connective  tissue  extending-  from  the  pia  mater  into  the 
underlying  tissue.  Find  the  posterior  median  septum,  and  the  anterior 
median  fissure.  How  can  you  always  distinguish  the  posterior  from 
the  anterior  surface  of  the  cord?  Note  the  difference  in  appearance 
between  the  white  matter  and  gray  matter.  Make  a  study  of  the  white 
matter,  noting  the  axis  cylinders  with  their  medullary  sheaths.  Find 
the  posterior  and  anterior  lateral  columns.  Make  a  study  of  the  gray 
matter,  observing  the  anterior  and  posterior  lateral  cornua.  Look  for 
the  anterior  and  posterior  roots  of  the  spinal  nerves.  Observe  the  cen- 
tral commissure  inclosing  the  central  canal.  Multipolar  ganglion  cells 
should  be  found  in  the  gray  matter.  Follow  out  an  axis  cylinder  until 
it  enters  the  white  matter.  Look  for  neuroglia.  Drawings. 

Laboratory  exercise  No.  25. — The  cerebrum.  Harden  in  Muller's  fluid, 
embed  in  paraffin,  and  stain  with  ha3matoxylin  and  eosin,  method  No.  8. 
In  examining  the  cerebrum,  search  first  for  the  pia  mater;  then  demon- 
strate the  cerebral  cortex  with  its  five  layers  made  up  of  cells  of  differ- 
ent forms  and  sizes;  and,  finally,  the  medulla,  consisting  chiefly  of  me- 
dullated  fibres.  The  layers  of  the  cerebral  cortex,  beginning  externally, 
will  be  arranged  in  the  following  order:  Granular  layer,  layer  of  small 
pyramidal  cells,  layer  of  large  pyramidal  cells,  layer  of  polymorphous 
cells,  and  the  layer  of  fusiform  cells.  Demonstrate  the  axis  cylinders 
and  their  collaterals;  observe  the  bundles  of  medullary  fibres  extend- 
ing between  the  cells.  Drawings. 

Laboratory  exercise  No.  26. — The  cerebellum.  Harden  in  Muller's 
fluid,  embed  in  paraffin,  and  stain  with  haBmatoxylin  and  eosin,  method 


90  NORMAL  HISTOLOGY. 

No.  8.  An  examination  of  the  cerebellar  cortex  will  exhibit  three  layers 
— the  molecular  layer,  the  layer  of  Purkinji's  cells,  and  the  granular 
layer,  located  internally.  The  white  matter  will  be  found  to  be  made 
up  of  medullated  fibres  and  neuroglia.  Observe  the  primary  and  sec- 
ondary convolutions.  Notice  the  cells  of  Purkinji  and  their  proto- 
plasmic processes.  Note  also  the  pia  mater.  Drawings. 

NERVOUS  TISSUE. 


A.  Cells.  B.  Fibres. 


A.  Cells:  (a)  Neuroblast;  (b)  Neuron;  (c)  Neuro-dendron ;  (d)  Unipolar  cell; 
(e)  Bipolar  cell;  (f)  Multipolar  cell;  (g)  First-type  cell;  (h)  Second-type  cell;  (i) 
G-liacell;  (j)  Axis  cylinder  process;  (k)  Collaterals;  (1)  Dendrites. 

B.  Fibre:  (a)  Neurilemma;  (b)  Medullary  sheath;  (c)  Axilemma;  (d)  Axis  cyl- 
inder; (e)  Nodes  of  Ranvier;  (f)  Internode:  (g)  Nerve  corpuscle. 

C.  Q-anglion,  exhibiting  cells  and  fibres  and  sheath. 

D.  Nerve:  (a)  Fibres;  (b)  Epineurium;  (c)  Perineurium;  (d)  Endoneurium. 

Spinal  Cord. 


Spinal  cord:  (a)  Pia  mater;  (b)  Septa;  (c)  Anterior  median  fissure;  (d)  Poste- 
rior median  fissure;  (e)  Anterior  lateral  column;  (f)  Posterior  lateral  column;  (g) 
Column  of  Q-oll;  (h)  Column  of  Burdoch;  (i)  Anterior  gray  commissure;  (j)  Poste- 
rior gray  commissure ;  (k)  Central  canal;  (1)  Anterior  Cornu;  (m)  Posterior  Cornu; 
(n)  Lateral  Cornu;  (o)  Motor  cells;  (p)  Column  cells;  (q)  Neuroglia. 


NERVOUS  TISSUE. 


Cerebrum. 


Cerebrum:  (a)  Dura  mater;  (b)  Arachnoid;  (c)Pia  mater;  (d)  Septa;  (e)  Cere- 
bral cortex;  (f)  Medulla;  (g)  Molecular  layer;  (h)  Layer  of  small  pyramidal  cells; 
(i)  Large  pyramidal  cells;  (j)  Layer  of  irregular  cells;  (k)  Layer  of  fusiform  cells; 
(1)  Medullated  fibres;  (m)  Axis  cylinder;  (n)  Neuroglia. 

Cerebellum. 


Cerebellum:  (a)  Pia  mater;  (b)  Cerebellar  cortex;  (c)  Molecular  layer;  (d) 
Layer  of  Purkinji's  cells;  (e)  Granular  layer;  (f)  Medulla;  (g)  Medullated  fibres; 
(h)  Neuroglia;  (i)  Primary  convolutions;  (j)  Secondary  convolutions;  (k)  Pur- 
kinji's cells  and  processes. 

[91] 


NORMAL  HISTOLOGY. 


CHAPTER  XI. 

THE  CIRCULATORY  SYSTEM. 

The  circulatory  system  includes  the  heart,  arteries,  veins,  and 
capillaries.  It  is  derived  from  the  mesoderm  of  the  embryo.  Its 
nervous  supply  is  received  from  the  sympathetic  system.  The  fol- 
lowing outline  exhibits  the  structural  elements  which  enter  into 
its  various  organs : 

OUTLINE  OF  CIRCULATORY  SYSTEM. 


Heart 


r  Layers  . 

, 

Annul! 
fibrosi.      1, 

Arteries 


Veins 


Cavities  . . . 


Valves 

Tunica  ad- 
ventia. . . 

Tunica  me- 
dia. . 


Tunica  in- 
tima  . . 


Visceral  endo- 
thelium. 

Pericardium <j   Fibrous  tissue. 

|   Areolar  tissue. 
[  Parietal    endo- 

thelium. 

Muscular  layer,  or 
myocardium •{   Striated  fibres. 


Endocardium.  . 


Auricles. 
Ventricles. 


Elastic  fibres. 
Substantia  pro- 

pria. 
Endothelium. 


Tunica  ad- 
ventia. . 


Tunica  me- 
dia.. 


Tunica  in- 
tima  . . 


(  Fibrous  connective  tissue. 
(  Endocardium. 

j  Fibrous  connective  tissue. 
(  Elastic  fibres. 

j  Involuntary  muscle. 
(  Elastic  tissue. 

T  Internal  elastic  membrane. 
<   Sub-endothelial  tissue. 
I  Endothelium. 

f  Connective  tissue. 
<j   Elastic  fibres. 
^  Smooth  muscle. 

f  Involuntary  muscle. 
I  Elastic  tissue. 

{Internal  elastic  membrane. 
Sub-endothelial  tissue. 
Endothelium. 
Valves. 


THE  CIRCULATORY  SYSTEM.  93 


Capillaries 4  Cement 

[  Sti 


f  Endothelial  cells. 
Cement. 
Stigmata. 


THE  HEART. 


The  heart  is  composed  of  three  distinct  layers — pericardium; 
muscular  layer,  or  myocardium;  and  endocardium. 

The  pericardium  is  lined  on  its  outer  and  inner  surfaces  with  a 
single  layer  of  endothelium.  Between  these  layers  are  fibrous  and 
areolar  tissues,  which  send  out  septa  into  the  myocardium. 

The  muscular  layer,  or  myocardium,  is  composed  of  striated 
fibres  which  branch,  and  the  branches  anastamose  with  each  other. 
The  fibres  run  in  all  directions,  interweaving  with  each  other,  thus 
making  possible  the  peculiar  contraction  of  the  heart.  The  fibre  is 
without  a  sarcolemma  and  has  centrally-located  nuclei. 

The  endocardium,  or  inner  layer,  is  composed  of  elastic  fibres, 
the  substance  proper,  and  endothelium.  The  substance  proper  con- 
tains smooth  muscle  fibres,  which  are  surrounded  by  a  delicate  peri- 
mysium. 

The  annuli  fibrosi  consist  of  ligaments  which  lie  between  the 
auricles  and  ventricles,  and  form  an  attachment  for  numerous 
muscle  fibres. 

The  valves  of  the  heart  are  modified  endocardium.  They  consist 
of  endocardium  and  fibrous  connective  tissue  which  is  continuous 
with  that  of  the  annuli  fibrosi. 

THE  ARTERIES. 

Arteries  comprise  three  coats — Tunica  adventitia,  tunica  media, 
and  tunica  intima.  The  tunica  adventitia  is  the  external  layer  and 
consists  of  bundles  of  connective  tissue  and  elastic  fibres,  longitudi- 
nally disposed.  The  tunica  media  is  composed  of  involuntary  mus- 
cle ancl  elastic  tissue,  circularly  disposed.  The  tunica  intima  con- 
sists of  the  internal  elastic  membrane,  which  is  structureless  in 
character ;  the  subendothelial  tissue,  which  consists  of  flattened  cor- 
puscles and  elastic  fibres ;  and  the  endothelium,  consisting  of  a  sin- 
gle layer  of  cells  lining  the  internal  cavity  of  the  artery. 


94  NORMAL  HISTOLOGY. 

VEINS. 

A  vein  also  consists  of  three  coats  similarly  named  to  those  of 
the  artery.  A  vein  differs  from  an  artery  in  being  thinner,  and  in 
having  a  preponderance  of  connective  over  muscular  and  elastic  tis- 
sues. 

The  tunica  adventitia  is  composed  of  bundles  of  connective  tissue, 
elastic  fibres,  and  involuntary  muscle,  which  intercross,  the  general 
arrangement  being  longitudinal.  In  the  tunica  media,  the  smooth 
muscle  fibres  are  circularly  arranged  and  are  associated  with  fibro- 
elastic  tissue.  The  tunica  intima  comprises  the  internal  elastic 
membrane,  the  subendothelial  tissue,  and  a  single  layer  of  polyhe- 
dral endothelial  cells. 

The  valves  of  the  veins  are  produced  by  an  infolding  of  the  in- 
tima. Their  surfaces  are  lined  with  endothelial  cells. 

CAPILLARIES. 

A  capillary  consists  of  a  single  layer  of  endothelial  cells  united 
to  each  other  by  a  cement  substance  and  exhibits  at  intervals  open 
spaces,  the  stigmata.  It  is  through  the  stigmata  that  the  leucocytes 
migrate  on  their  mission  to  build  up  the  worn-out  tissues  of  the 
body.  Capillaries  which  supply  nutrition  to  blood-vessels  are  called 
vasa  vasorum.  The  diameter  of  a  capillary  averages  about  8  /*. 

Laboratory  exercise  No.  27. — The  heart.  Fix  and  harden  with  alco- 
hols, embed  in  paraffin,  and  stain  with  haematoxylin,  method  No.  6. 
In  examining  your  preparation,  search  first  for  the  pericardium,  and 
demonstrate  its  endothelial  lining-  and  fibrous  connective  tissue;  then 
examine  the  myocardium,  observing  the  course  of  the  fibres,  their 
branching  and  anastomosing,  and  the  centrally  located  nuclei;  finally, 
examine  the  endocardium,  composed  of  fibrous  tissue,  elastic  fibres, 
and  endothelium.  If  possible,  examine  the  structure  of  a  valve.  Search 
for  blood-vessels.  Drawings. 

Laboratory  exercise  No.  28. — Arteries  and  veins.  Harden  the  great 
aorta  in  alcohol,  embed  in  paraffin,  and  stain  with  haematoxylin  and 
eosin,  method  No.  8.  Examine  with  H.  P.  and  make  out  the  three  coats 
— the  tunica  adventitia  on  the  outside,  tunica  media  in  the  middle,  and 
tunica  intima  on  the  inside.  Name  the  structures  which  enter  into 
these  coats.  A  study  of  veins  may  be  made  from  sections  of  the  um- 
bilical cord,  the  lungs,  or  the  tongue.  Drawings. 


CIRCULATORY  SYSTEM. 


Heart. 


Heart:  (a)  Pericardium,  exhibiting  endothelial  layers  and  intervening  fibrous 
tissue;  (b)  Myocardium:  (c)  Endocardium,  with  its  elastic  fibres,  substantia  pro- 
pria  and  endothelium;  (d)  Annuli  flbrosi;  (e)  Anastomosing  striated  fibres;  (f) 
Nucleus;  (g)  Valve. 

A.    Artery.  B.  'Capillary  and  Vein. 


A.  Artery:  (a)  Tunica  adventitia;  (b)  Tunica  media:  (c)  Tunica  intima. 

B.  Vein :    (a)  Tunica  adventia;   (b)  Tunica  media;   (c)  Tunica  intima;   (d) 
Capillary. 

[95] 


96 


NORMAL  HISTOLOGY. 


CHAPTER  XII. 

THE  LYMPHATIC  SYSTEM. 

The  lymphatic  system  includes  lymphatic  tissues,  vessels,  organs. 
Lymphatic  tissue  is  immediately  concerned  in  the  production  of 
lymph  corpuscles.  The  yellowish  fluid  contained  in  the  lymphatic 
vessels  is  the  lymph.  The  structures  of  this  system  are  derived  from 
the  epiderm  and  mesoderm. 


OUTLINE  OF  THE  LYMPHATIC  SYSTEM. 


Lymphatic  tissue  . . 


Lymphatic  vessels. 


Adenoid  tissue,  or  connective  tissue  reticulum. 
Lymphoid  cells. 


Outer  coat. 
Middle  coat. 
Inner  coat. 

(  Simple  nodules , 


Lymphatic  follicles  •{ 


f  Capsule. 

[  Adenoid  tissue  and  lym- 
phoid  cells. 

f  Capsule  and  trabeculae. 

f  Corticalfollicles. 


Compound  lymphatic 
follicles 


Cortex 


I  Germinal  center. 


Medulla. 
Hilum. 
Sinuses. 
Reticulum. 


Spleen . 


Capsule 


Splenic 
pulp. . 


Derivation 

Thymus  body <j   Capsule. 

Lobes . . . 


Serous  coat. 
Fibrous  coat. 
Trabeculse. 


[  Lobes...] 


Divisions . 


Structure 


Septa. 
Lobules . . 


Loose  adenoid  tissue. 

Dense  adenoid  tissue,  or 
Malpighian  corpuscles. 

Connective  tissue  reticu- 
lum. 

{Leucocytes. 
Red  corpuscles. 
Lymphoid  cells. 
Pigment  granules. 


Cortex. 

Medulla. 

Hassal's  corpuscles. 


THE  LYMPHATIC  SYSTEM.  97 

f  Capsule. 
Adenoid  tissue. 

Tonsils Mucous  g-lands. 

[  Blood  and  lymph  corpuscles. 

LYMPHATIC  TISSUE. 

Lymphatic  tissue  is  composed  chiefly  of  two  structures:  (1)  A 
connective  tissue  reticulum.  This  is  commonly  known  as  adenoid, 
or  retiform  tissue.  (2)  The  lymphoid  cells,  which  are  held  in  the 
meshes  of  the  reticulum.  These  escape  into  the  lymphatic  vessels 
and  are  there  known  as  the  lymph  corpuscles.  They  eventually 
become  the  leucocytes  of  the  blood. 

LYMPHATIC  VESSELS. 

The  lymphatic  vessels  are  irregular  in  outline,  due  to  folds  in 
the  endothelium,  which  serve  as  imperfect  valves.  The  wall  of  each 
vepsel  exhibits  three  coats.  The  inner  coat  consists  of  endothelium, 
the  middle  of  smooth  muscle,  and  the  outer  of  connective  tissue. 

LYMPHATIC  FOLLICLES. 

These  have  been  classified  as  simple  .nodules  and  compound  lym- 
phatic nodes.  The  simple  nodule  consists  of  a  capsule  and  adenoid 
tissue  with  enclosed  lymphoid  cells.  The  compound  lymphatic 
node  exhibits  capsule,  reticulum  of  connective  tissue,  cortex,  and 
medulla.  The  capsule  is  the  sheath  of  connective  tissue  which  cov- 
ers the  node  and  from  which  septa,  or  trabeculas,  extend  into  its 
substance.  The  cortex  is  the  outer  zone  of  the  body,  and  consists 
of  the  cortical  follicles  and  the  germinal  center.  The  cortical  folli- 
cles are  the  laboratories  in  which  are  manufactured  the  leucocytes. 
The  germinal  center  is  a  light  spot  within  the  follicle,  characterized 
by  the  presence  of  kinetic  figures.  The  medulla  is  the  central  por- 
tion of  the  gland.  It  contains  the  medullary  bands,  which  are  sim- 
ply extensions  of  the  trabeculae  into  its  substance.  TJhis  mesh- work 
formed  by  the  subdivision  of  the  trabeculae  constitutes  the  reticulum. 
The  Jiilum  is  an  infolding  of  the  capsule  upon  a  blood-vessel  or 
lymph  channel  at  its  point  of  entrance  into  the  gland.  Sinuses  are 
the  open  spaces  between  the  adenoid  tissue  and  trabeculae. 


98  NORMAL  HISTOLOGY. 

THE  SPLEEN. 

The  spleen  has  the  structure  of  a  large  lymphatic  node.  It  con- 
sists of  a  capsule  and  splenic  pulp.  The  capsule  consists  of  two 
coats — an  outer  serous  and  inner  fibrous  coat.  Extending  from 
the  capsule  into  the  piilp  are  trabeculw,  which  divide  and  subdi- 
vide, forming  a  reticulum  of  connective  tissue.  The  splenic  pulp 
comprises  the  loose  adenoid  tissue  and  the  dense  adenoid  tissue.  The 
dense  adenoid  tissue  is  disposed  in  spherical  masses  which  are  situ- 
ated in  the  forks  of  the  arteries.  Each  mass  is  pierced  by  an  ar- 
tery. These  dense  spherical  masses  of  the  pulp  are  called  Malpighi- 
an  corpuscles.  Their  structure  does  not  differ  materially  from  that 
of  the  loose  tissue.  The  pulp,  as  with  other  lymphatic  structures, 
consists  of  a  connective  tissue  reticulum,  holding  in  its  meshes  leu- 
cocytes, red  corpuscles,  lymph oid  cells,  and  pigment  granules. 

THYMUS  BODY. 

This  structure  is  derived  from  the  hypoderm,  and  in  its  early 
development  is  chiefly  epithelial  in  character,  but  later  becomes  in- 
vaded with  mesodermic  tissues,  until  it  assumes  a  lymphatic  type. 
After  the  second  }rear  it  loses  its  characteristic  structure,  and  its 
tissues  are  replaced  by  fibrous  tissue  and  fat.  It  consists  of  a  cap- 
sule and  a  pulp,  which  is  divided  into  lobes.  The  lobes  are  separated 
from  each  other  by  septa  derived  from  the  capsule.  The  lobes  are 
divided  into  lobules,  each  lobule  consisting  of  adenoid  tissue,  the 
outer,  looser  portion  being  called  the  cortex,  while  the  inner,  denser 
portion  is  the  medulla.  Hassal's  corpuscles  are  masses  of  em- 
bryonic epithelial  cells  found  in  the  medulla, 

TONSILS. 

The  tonsils  are  composed  of  diffuse  adenoid  tissue,  containing 
from  ten  to  eighteen  lymph  follicles.  There  is  a  fibrous  capsule,  be- 
neath which  are  the  connective  tissue  reticulum,  the  lymphatic  fol- 
licles, mucous  glands  between  the  follicles,  and  lymphoid  cells. 

Laboratory  exercise  No.  29.— The  spleen.  Harden  in  Erlicki's  fluid 
or  alcohol,  embed  in  paraffin,  and  stain  with  haematoxylin  and  eosin, 
method  No.  8.  Examine,  first,  the  capsule,  and  its  extensions,  or  tra- 
beculae,  penetrating  the  splenic  pulp.  Distinguish  between  the  loose 
and  dense  adenoid  tissue.  Examine  the  structure  of  a  Malpighian  cor- 
puscle with  H.  P.,  noting  the  connective  tissue  reticulum  and  the 
lymphoid  cells.  Describe  the  disposition  of  arteries,  veins,  and  lym- 
phatics in  the  spleen.  Has  the  spleen  a  duct?  Drawings. 


LYMPHATIC  SYSTEM. 


Lymphatic  Follicle. 


Compound  lymphatic  node:  (a)  Capsule;  (b)  Cortex;  (c)  Cortical  follicle;  (d) 
Germinal  center;  (e)Mudulla;  (f)  Hilum;  (g)  Sinus;  (h)  Reticulum;  (i)  Lymphoid 
cells. 


Spleen. 


Spleen:  (a)  Capsule— serous  coat;  (b)  Fibrous  coat;  (c)  Trabecula;  (d)  Loose 
adenoid  tissue;  (e)  Malpighian  corpuscle;  (f)  Reticulum;  (g)  Lymphoid  cells; 
(h)  Leucocytes;  (i)  Blood  vessels. 

[99] 


100  NORMAL  HISTOLOGY. 


CHAPTEE  XIII. 

MEMBRANES  AND  GLANDS. 
I.  MEMBRANES. 

Membranes  are  disposed  upon  surfaces  in  the  interior  of  the  body. 

OUTLINE  OF  MEMBRANES. 


f  Serous  membranes  proper. 

I 
Serous  membranes -{  Synovial  membranes. 

Endothelium. 
Epithelium. 


Mucous  membranes 


Basement  membrane. 

(  Fibrous  connective  tissue. 
Stroma  ..........  <J 

t  Elastic  fibers. 
Muscular  is  mucosee. 


p     .-,•, 

(_  Occasional  structures  .......  <J  Glands. 

{  Lymphoid  cells. 

There  are  two  kinds  of  membranes  —  serous  and  mucous.  Serous 
membranes  cover  the  outside  surfaces  of  the  alimentary  tract  and 
respiratory  organs,  as  well  as  the  articular  ends  of  bones  and  other 
structures.  They  include  three  varieties  —  serous  membranes  proper, 
synovial  membranes,  and  endothelium.  Serous  membranes  proper 
are  composed  of  fibrous  tissue  and  elastic  fibres,  with  a  superficial 
layer  of  endothelium.  Synovial  membranes  include  the  capsules 
which  envelop  the  ends  of  joints  and  the  sheaths  in  which  tendons 
glide.  They  are  characterized  by  the  viscid  fluid  —  the  synovia  — 
which  they  secrete.  Endothelium  consists  of  a  single  layer  of  flat- 
tened endothelial  cells. 

Mucous  membranes  line  all  surfaces  which  are  directly  or  indi- 
rectly in  communication  with  the  external  atmosphere.  The  struc- 
ture of  the  mucous  membrane  exhibits  the  following  elements: 
(1)  The  epithelium.  This  may  be  simple  or  stratified.  It  may  be 
squamous,  columnar,  or  ciliated.  Columnar  and  ciliated  epithelia 


MEMBRANES  AND  GLANDS.  101 

are  usually  provided  with  goblet  cells,  whose  function  is  to  produce 
mucus.  With  squamous  stratified  epithelium,,  the  mucus  is  usually 
produced  by  glands  located  in  the  stroma,  (2)  Basement  mem- 
brane. This  occurs  as  a  mere  line  beneath  the  epithelial  layer.  It 
is  sometimes  called  the  membrana  propria,  It  is  made  up  of  flat- 
tened cells,  either  united  edge  to  edge,  or  held  together  by  anasta- 
mosing  processes.  On  one  side,  this  membrane  supports  the  epithe- 
lium ;  while  on  the  other,  it  is  in  close  connection  with  the  capil- 
laries. (3)  The  stroma.  This  structure  lies  directly  beneath  the 
basement  membrane,  and  is  composed  of  fibrous  connective  tissue 
and  elastic  fibres,  and  is  provided  with  a  rich  supply  of  blood-vessels 
and  lymphatics.  (4)  The  Muscularis  mucosce.  This  is  a  shallow, 
muscular  sheath,  which  forms  the  lower  limit  of  the  mucous 
membrane.  It  is  composed  of  circular  and  longitudinal  strata 
of  involuntary  muscle  fibres.  (5)  Occasional  structures.  In.  addi- 
tion to  the  structures  above  named,  papilla?,  villi,  glands,  and  lym- 
phoid  cells  occur  in  the  mucous  membrane.  Papillce  are  conical  ele- 
vations of  the  stroma,  which  are  supplied  with  blood-vessels  and 
nerves,  and  covered  with  epithelium.  They  occur  in  the  tongue, 
oesophagus,  etc.  The  villi  occur  chiefly  in  the  small  intestine. 
They  are  provided  with  blood  capillaries  and  lacteals,  and  are  de- 
signed to  increase  the  absorbing  surface  of  the  intestine.  The 
glands  which  occur  are  of  two  varieties — tubular  and  sacular.  The 
mucous  glands  are  located  in  the  epithelial  layer  and  stroma  of 
mucous  membranes,  and  are  concerned  in  the  elaboration  of  mucin. 

IT.  GLANDS. 

Glands  are  of  two  kinds — serous  and  mucous.  A  serous  gland  is 
characterized  by  spherical,  granular  cells,  with  central  nuclei,  which 
are  readily  stained  by  carmine.  Mucous  glands  are  not  readily 
stained  by  carmine.  The  nuclei  are  usually  upon  the  cell  surface. 

OUTLINE  OF  GLANDS. 


f  Serous  glands. 

Kinds \ 

[  Mucous  glands. 


102  NOKMAL  HISTOLOGY. 

f  Simple. 

(Tubular. . .. < 
{  Compound. 
f  Simple. 

^  Saccular < 

[  Compound,  or  race- 
mose. 

(Basement  membrane. 
Secretory  cells. 
Structure  . .  .  <j    Lumen. 


Duct. 
Development. 

There  are  two  characteristic  forms  of  glands  —  tubular  and  sac- 
ular  —  either  of  which  may  be  simple  or.  compound.  A  simple  tu- 
bular gland  is  cylindrical  and  elongated/  consisting  of  a  basement 
membrane  lined  internally  with  cuboidal  or  columnar  cells  which 
constitute  the  fundus,  the  opening  from  the  gland  being  styled  the 
duct.  The  empty  space  within  the  gland  is  the  lumen.  When  the 
lumen  becomes  divided  by  one  or  more  partitions,,  producing  a  clus- 
ter of  simple  glands,  we  then  have  a  compound  tubular  gland.  The 
saccular  gland  resembles  in  structure  that  of  the  tubular  variety,  but 
in  form  it  is  broader,  becoming  inflated  like  a  sac.  A  group  of 
simple  saccular  glands  gives  rise  to  the  compound  saccular,  or  race- 
mose, variety.  The  chief  function  of  glands  is  that  of  secretion. 
The  salivary  glands,  pancreas,  and  intestinal  glands  are  illustra- 
tions. 

III.  PAROTID  GLAND. 

The  Parotid  gland  is  a  compound  saccular  gland  of  the  serous 
type.  Its  tissues  are  derived  from  the  mesoderm  and  epiderm.  Its 
function  is  to  produce  saliva,  a  watery  substance  containing  mi- 
nute granules. 

OUTLINE  OF  THE  PAROTID  GLAND. 

f  Secretory  cells. 
Acini.  Basement  mem- 


Ductules. 

Lobes <!  Connective  tissue. 

Stenson's  duct. 
Ducts 

Salivary  tubes. 


MEMBRANES  AND  GLANDS.  103 

Structure, — There  is  an  investing  capsule  of  fibrous  connective 
tissue  which  sends  out  septa  into  the  substance  of  the  gland;  these 
septa  divide  the  gland  into  lobes  and  lobules.  Each  lobule  is  com- 
posed of  acini,  each  acinus  consisting  of  a  basement  membrane  lined 
with  secreting  cells.  The  lumen  of  the  acinus,  or  alveolus,  leads  to 
the  alveolar  ductule,  the  ductules  discharging  into  the  salivary 
tubes;  the  salivary  tubes  into  the  intermediate  tubes;  and  these  into 
Stenson's  duct,  which  is  the  large  excretory  duct.  Stenson's  duct  is 
composed  of  fibro-elastic  tissue  lined  internally  with  a  single  layer 
of  columnar  epithelium. 

Laboratory  exercise  No.  30. — Parotid  gland.  Harden  in  alcohol,  em- 
bed in  paraffin,  and  stain  with  carmine,  method  No.  3.  It  is  well  in 
demonstrating-  most  structures  to  begin  with  the  external,  simpler 
parts,  and  work  inward  to  those  that  are  more  complex.  In  this  case 
demonstrate  first  the  capsule  and  its  penetrating1  septa.  Note  how  the 
giand  is  diyided  into  lobes  and  lobules  by  the  subdividing-  septa.  Ob- 
serve an  acinus,  and  note  the  form  of  the  cell.  Find  Stenson's  duct  and 
note  its  structure.  Drawings. 

IV.  THE  PANCREAS. 

The  pancreas  is  a  compound  tubular  giand  of  the  serous  type. 
The  following  outline  exhibits  its  structure: 


OUTLINE  OF  THE  PANCREAS. 


Capsule. 
Septa. 


f  Acini. 


Lobes <  Gland  cells. 

{  Bodies  of  Langerhans. 
Pancreatic  Duct. 

Intermediate  tubules. 

Structure, — The  pancreas  has  the  usual  investing  capsule  of  con- 
nective tissue,  from  which  extend  numerous  septa  dividing  the  or- 
gan  into  lobes.  The  lobes  consist  of  acini,  whose  basement  mem- 
branes are  lined  with  short  cylindrical  or  conical  cells.  Each 
cell  is  characterized  by  two  zones — a  clear  peripheral  zone  contain- 
ing the  nucleus,  and  the  zone  next  the  lumen  which  contains  the 
so-called  zymogen  granules.  The  bodies  of  Langerhans  are  imper- 


104:  NORMAL  HISTOLOGY. 

feet  acini  which  appear  as  less  dense  rounded  areas  among  the  ordi- 
nary tissue.  For  the  elimination  of  the  products  of  secretion,  the 
pancreas  is  provided  with  ductules,  intermediate  tubules,  and  the 
pancreatic  duct.  The  last  is  composed  of  fibrous  connective  tissue 
lined  internally  with  epithelium  and  provided  with  minute  mucoas 
glands. 

Laboratory  exercise  No.  31. — Pancreas.  Harden  with  alcohol,  embed 
in  paraffin,  and  stain  with  carmine.  Make  out  the  following  structures: 
The  capsule,  septa,  lobes,  acini,  basement  membrane,  secretory  cells, 
containing  nuclei  and  granules,  intermediate  tubules,  and  pancreatic 
duct.  Drawings. 

MEMORANDA. 


GLANDS. 


Forms  of  Glands. 


A.  Simple  tubular  gland:   (a)  Basement  membrane;  (b)  Secretory  cells;  (c) 
Lumen;  (d)  Duct. 

B.  Compound  tubular  gland:  (a)  Basement  membrane;  (b)  Cells;  (c)  Duct- 
ule;  (d)  Duct. 

C.  Simple  saccular  gland. 

D.  Compound  saccular  gland. 

A.    Parotid  Gland.  B.    Pancreas. 


A.  Parotid  gland:  (a)  Capsule;  (b)  Septa;  (c)  Lobe;  (d)  Lobule;  (e)  Acinus; 
(f)  Secretory  cells;  (g)  Basement  membrane;  (h)  Lumen;  (i)Ductule;  (j)Stenson's 
duct;  (k)  Connective  tissue. 

B.  Pancreas:  (a)  Capsule;  (b)  Septa;  (c)  Lobe;  (d)  Acinus;  (e)  Gland  cells; 
(f)  Bodies  of  Langerhans;  (g)  Pancreatic  duct;  (h)  Intermediate  tubules. 

[105] 


106 


NORMAL  HISTOLOGY. 


CHAPTEK  XIV. 

THE  SKIN. 

The  epidermis  of  the  skin  is  derived  from  the  epiderm  of  the 
embryo,  while  the  corium  is  largely  of  mesodermic  origin.  Its  chief 
functions  are  protection,  respiration,  and  excretion. 

OUTLINE  OF  SKIN. 


Derivation. 


Structure 


Epidermis 


Stratum  corneum. 
Stratum  lucidum. 
Stratum  granulosum. 
Stratum  malpighii. . . . 


Pigment  granules. 
Prickle  cells. 


Appendages 


Coriuni 


Glands 


Nails 


f  Fibrous  connective  tissue. 
. . . .  •)   Elastic  fibres. 

L  Blood  vessels,  nerves,  etc. 


{Sebaceous. 

Sudoriferous. 

(  Body 

j  Free  edge. 

1   Nail  wall. 

.  .  {   Root  .  . 

\   Nail  fold. 

Nail  bed. 
Matrix. 

Cuticle. 
Shaft <!  Cortex. 

Medulla. 

{  Bulb. 

Root <|   Papilla. 

I  Follicle. 


Structure, — The  skin  consists  of  two  layers — the  epidermis,  or 
cuticle,  and  corium,  or  cutis.  The  epidermis  is  constituted  of  strati- 
fied squamous  epithelium  disposed  in  four  layers.  These  are  the 
stratum  corneum,  stratum  lucidum,  stratum  granulosum,  and 
stratum  Malpighii.  The  stratum  corneum  is  superficial  and  is  com- 
posed of  flattened  corneous  cells  which  have  lost  their  protoplasm 
and,  by  desquamation,  are  continually  cast  off.  The  stratum  luci- 
dum, occurs  next,  and  comprises  a  narrow  zone  in  which  the  cells 
exhibit  an  approach  to  the  flattened  scales  of  the  outer  stratum. 


THE  SKIN.  107 

The  stratum  granulosum  contains  cells  more  flattened  than  those  of 
the  succeeding  layer,  and  possesses  granular  particles,  called  eleidin, 
which  have  an  affinity  for  carmine.  In  the  stratum,  Malpighii,  the 
cells  are  rounded,  or  even  columnar,  in  shape.  Some  of  the  cells 
are  connected  by  protoplasmic  processes,  which  give  rise  to  the  so- 
called  prickle  cells.  In  this  layer  occur  the  pigment  granules  that 
give  color  to  the  skin.  Beneath  the  epidermis  is  a  basement  mem- 
brane. The  corium  comprises  all  that  part  of  the  skin  underlying 
the  epidermis.  It  consists  of  two  layers — the  stratum  papillare  and 
the  stratum  reticulare.  The  stratum  papillare  contains  the  papillae, 
which  are  conical  elevations  of  the  corium  into  the  epidermis.  They 
are  supplied  with  blood-vessels  and  nerves,  a  nerve-ending  occurring 
at  the  summit  of  each  papilla.  The  corium  is  composed  of  fibrous 
connective  tissue,  elastic  fibres,  blood-vessels,  nerves,  glands,  and  a 
small  amount  of  muscular  tissue.  The  sebaceous  glands  are  lo- 
cated in  the  corium  papillare,  while  the  sudoriferous  glands  occur 
in  the  corium  reticulare  or  subcutaneous  tissue.  The  corium  rests 
upon  a  subcutaneous  structure,  which  consists  chiefly  of  areolar, 
adipose,  and  fibrous  connective  tissues. 

APPENDAGES. 

The  nails. — Nails  are  derived  from  the  epidermis,  and  are  com- 
posed of  horny  cells.  The  structure  of  the  nail  comprises  the  body, 
root,  nail-bed,  and  matrix.  The  body,  or  exposed  part,  terminates 
in  a  free-edge,  while  its  sides  are  protected  by  the  nail- walls.  The 
groove  which  receives  the  root  is  the  nail-fold.  That  portion  of  the 
epidermis  upon  which  the  nail  rests  is  the  nail-bed,  and  the  basal 
portion  of  the  nail-bed  upon  which  the  root  rests  is  the  matrix.  The 
matrix  and  nail-bed  are  constituted  of  the  stratum  Malpighii,  while 
the  body  and  root  represent  the  stratum  lucidum,  the  stratum  cor- 
neum  being  absent.  The  portion  which  is  actively  engaged  in  pro- 
ducing the  nail-body  is  the  matrix.  The  nail,  therefore,  grows  in 
length,  thickness,  and  width  by  the  formation  of  new  cells  by  the 
matrix.  The  body  consists  of  horny  plates. 

The  hair. — Hair  is  a  modification  of  the  epidermis,  and  is  pro- 
duced by  an  infolding  of  the  epidermis  and  a  differentiation  of  the 
lower  cells  of  the  follicle  thus  produced.  The  hair  consists  of  two 


108  NORMAL  HISTOLOGY. 

parts,  the  shaft  and  the  root.  The  shaft  comprises  the  cuticle,  or 
outer,  imbricated  layer  of  epithelial  cells ;  the  cortex,  or  middle  lay- 
er, composed  of  elongated,  horny,  epithelial  cells,  which  contain 
the  pigment  granules  that  give  color  to  the  hair;  and  the  medulla. 
which  constitutes  the  central  cylinder  and  is  composed  of  cuboidal 
cells  filled  with  minute  air  vesicles  which  appear  as  dark  granules. 
These  air  vesicles  also  contribute  to  the  color  of  the  hair.  The 
follicle  is  the  receptacle  of  the  hair,  produced  by  the  infolding  of 
the  epidermis.  Above  the  sebaceous  glands  it  consists  of  a  fibrous 
coat,  stratum  lucidum,  and  stratum  corneum,  but  beneath  them  the 
stratum  corneum  disappears.  The  root  and  bulb  of  the  hair  exhibit 
a  continuation  of  the  same  essential  structures  as  found  in  the  shaft. 
The  papilla  is  a  conical  elevation  of  the  corium  into  the  base  of  the 
follicle  and  hair  bulb.  It  contains  pigment  cells  and  blood-vessels, 
which  provide  nourishment. 

A  transverse  section  of  a  hair  varies  in  outline  with  different 
races.  The  hair  of  the  Mongolian  (Japanese)  exhibits  a  circular 
outline ;  that  of  a  German  is  oval ;  that  of  a  Negro  is  flattened-ovate ; 
while  that  of  the  Papuan  is  still  more  flattened  and  crescent-shaped. 
The  hair  is  provided  with  sebaceous  glands,  which  are  of  the  simple 
and  compound  saccular  type.  These  open  into  the  hair  follicles  near 
their  upper  extremity.  The  sebum,  or  secretion,  which  they  dis- 
charge upon  the  surface  of  the  hair  is  designed  to  oil  it  and  keep  it 
in  a  healthy  condition.  Each  hair  is  also  provided  with  a  muscle, 
ihearrector  pili  (composed  of  smooth  muscle  fibre),  which  extends 
obliquely  from  the  deeper  portion  of  the  follicle  to  the  upper  por- 
tion of  the  corium. 

Sebaceus  glands. — These  are  of  the  simple  or  compound  sac- 
cular type,  and  are  located  in  the  stratum  papillare  of  the  corium. 
They  consist  of  acini,  with  secreting  cells,  and  a  short  duct. 

The  sudoriferous  glands. — The  sweat  glands  are  of  the  simple 
tubular  variety.  The  coil  of  the  gland  is  located  in  the  subcu- 
taneous tissue,  and  consists  of  a  basement  membrane  lined  with  se- 
creting cells.  The  excretory  duct  extends  through  the  corium  and 
epidermis  by  a  sinuous  course  until  it  reaches  the  stratum  corneum, 
when  it  becomes  spiral,  terminating  upon  the  surface  of  the  skin 
in  a  rounded  pit. 


THE  SKIN.  109 

Laboratory  exercise  No.  32. — The  skin.  Harden  portions  of  the  scalp 
and  palm  of  the  hand  in  alcohol,  embed  in  paraffin,  and  stain  with 
haematoxylin  and  eosin,  method  No.  8.  Make  a  study  of  the  structures 
described  above,  noting1  especially  the  stratum  corneum,  stratum  luci- 
dum,  stratum  granulosum,  and  stratum  Malpigiiii  of  the  epidermis. 
Observe  the  membrana  propria  which  forms  a  supporting-  base  for  the 
squamous  cells.  Note  the  difference  in  form  of  the  cells  of  the  different 
layers.  In  the  corium,  observe  the  conical  elevations,  or  papillae,  and 
the  hair  follicles  which  extend  into  its  structures.  The  corium  is  made 
up  chiefly  of  connective  tissue  filled  with  blood-vessels  and  nerves.  In 
the  subcutaneous  tissue,  search  for  sweat  glands  and  trace  the  excre- 
tory duct  to  the  surface.  Make  a  study  of  the  hair,  both  T.S.  and  L.S., 
and  demonstrate  the  shaft,  root,  bulb,  papilla,  hair  follicle,  cuticle,  cor- 
tex, and  medulla.  Drawing's. 

MEMORANDA. 


THE  SKIN  AND  ITS  APPENDAGES. 


The  Skin. 


Skin:  (a)  Epidermis;  (b)  Stratum  corneum;  (c)  Stratum  lucidum;  (d)  Stratum 
granulosum:  (e)  Stratum  malpighii:  (f)  Prickle  cells;  (g)  Corium;  (h)  Fibres  of 
connective  tissue;  (i)  Blood  vessels;  (j)  Nerve  endings;  (k)  Papilla;  (1)  Sweat 
gland;  (m)  Duct  of  same;  (n)  Subcutaneous  tissue. 


Hair. 


Hair:  (a)  Follicle:  (b)  Shaft;  (c)  Cuticle;  (d)  Cortex;  (e)  Medulla;  (f)  Root; 
(g)  Bulb;  (h)  Papilla;  (i)  Sebaceous  gland;  (j)  Hair  muscle;  (k)  Hair  of  German; 
(1)  Hair  of  Negro;  (m)  Hair  of  Japanese;  (n)  Hair  of  Papuan. 
[110] 


NOKMAL  HISTOLOGY.  Ill 


CHAPTEE  XV. 

THE  ALIMENTARY  CANAL. 

The  alimentary  canal  is  derived  from  the  hypoderm  and  meso- 
derm.  The  squamous  epithelium  which  lines  the  oesophagus  is  of 
epidermic  origin.  The  columnar  epithelium  which  lines  the  ali- 
mentary tract  from  the  cardiac  orifice  onward  is  derived  from  the 
hypoderm.  The  connective  tissue  and  muscles  of  the  tract  are  of 
mesodermic  origin.  A  careful  study  of  the  subjoined  outlines  will 
indicate  to  the  student  the  very  close  analogy  between  the  different 
structures  of  the  canal.  The  chief  differences  will  be  found  in  the 
pharynx  and  oesophagus.  The  upper  half  of  the  pharynx  is  lined 
with  ciliated  epithelium,  its  lower  half  and  the  whole  course  of  the 
oesophagus  being  provided  with  stratified  squamous  epithelium.  The 
stomach  and  intestine  have,  instead,  columnar  epithelium.  The 
pharynx  and  oesophagus  are  provided  with  striated  muscle  fibre, 
whereas  the  stomach  and  intestine  have  only  smooth  muscle.  The 
four  coats  which  are  present  in  all  these  structures  are  the  mucosa, 
sub-mucosa,  muscular  coat,  and  serous,  or  fibrous,  coat.  The  mouth 
is  lined  with  stratified  squamous  epithelium,  beneath  which  is  the 
tunica  propria,  or  connective  tissue  stroma,  which  consists  of  inter- 
lacing bundles  of  fibrous  connective  tissue  containing  elastic  fibres. 
There  are  numerous  papillae  in  the  tunica  propria,  and  a  large  sup- 
ply of  small  mucous  racemose  glands. 

ALIMENTARY  CANAL. 


f  Squamous  epithelium. 
,.,  !   Membrana  propria. 

Mucosa Stroma. 

Muscularis  mucosse. 

Fibrous  connective  tissue. 

Sub-mucosa <!   Elastic  fibres. 

Glands. 
(Esophagus. 

f  Circular  muscle  layer. 


Muscular  coat 


\  Longitudinal  muscle  layer. 
Fibrous  connective  tissue. 


Serous  coat. 

Elastic  fibres. 


112 


NORMAL  HISTOLOGY. 


f  Mucosa. 


Columnar  epithelium. 

Membrana  propria. 

Stroma. 

Peptic  and  pyloric  glands. 

Muscularis  mucosee. 

f  Connective  tissue. 


Stomach «{  L  Vessels. 

f  Circular  muscle  layer. 

Muscular  coat <( 

[_  Longitudinal  muscle  layer. 

(  Connective  tissue. 

Serous  coat -j 

I  Endothelium. 

f  Columnar  epithelium. 
Basement  membrane. 
Stroma. 

f  Mucosa <{   Capillaries  and  lacteals. 

Muscularis  mucosse. 

Villi. 

Glands  of  Lieberkuhn. 

f  Connective  tissue. 

Sub-mucosa <|    Vessel. 

Small  intestine. ..  <{  f  Brunner's  glands. 

(.  Glands.  \  Solitary  glands. 
[  Peyers'  patches. 

f  Circular  layer. 

Muscular  coat \ 

[  Longitudinal  layer. 

Serous  coat. 

Columnar  Epithelium. 
Basement  membrame. 
Glands  of  Lieberkuhn. 

Muscularis  mucosee. 
Vessels. 

Solitary  glands. 

Sub-mucosa <{   Peyers'  patches. 

Large  intestine. . .  •{  t  Connective  tissue. 

f  Circular  layer. 

Muscular  coat < 

1^  Longitudinal  layer. 

Serous  coat. 


THE  ALIMENTARY  CANAL.  113 

THE  (ESOPHAGUS. 

The  oesophagus  contains  four  characteristic  coats — the  mucosa, 
the  sub-mucosa,  the  muscular  coat,  and  the  fibrous  coat. 

The  mucosa  consists  of  stratified  squamous  epithelium  resting 
upon  a  tunica  propria,  or  connective  tissue  stroma,  beneath  which 
is  a  thin  layer  of  involuntary  muscle,  the  muscularis  mucosw.  The 
tunica  propria  is  composed  of  fibrous  connective  tissue  and  contains 
blood-vessels  and  lymphatics. 

The  sub-mucosa  lies  beneath  the  muscularis  mucosas,  and  con- 
sists of  loose  connective  tissue,  containing  blood-vessels,  nerves,  and 
glands  of  the  racemose  variety. 

The  muscular  coat,  in  the  upper  end  of  the  oesophagus,  is  com- 
posed of  striated  fibres ;  in  the  lower  end,  of  smooth  muscle ;  while 
the  middle  portion  contains  both  smooth  and  striated  fibres. 

The  fibrous  coat  envelops  the  muscular  coat,  contains  elastic  tis- 
sue, and  forms  an  attachment  to  the  adjacent  areolar  tissue. 

Laboratory  exercise  No.  33. — Tfie  (Esophagus.  Harden  in  corrosive 
sublimate,  embed  in  celloidin,  and  stain  with  carmine,  method  No.  3. 
Examine  with  L.  P.  Demonstrate  the  epithelial  layer,  stroma  and  mus- 
cularis mucosse  of  the  mucosa.  Search  for  blood-vessels,  nerves,  and 
glands  in  the  sub-mucosa.  Examine  the  muscular  coat,  and  determine 
from  your  preparation  the  part  of  the  ossophagus  from  which  the  tissue 
was  obtained.  Note  the  structure  of  the  fibrous  coat.  Is  there  an  endo- 
thelial  layer?  Do  you  find  any  investing  areolar  tissue? 

THE  STOMACH. 

Tlie  stomach  has  the  usual  coats — mucosa,  sub-mucosa,  muscular 
coat,  and  serous  coat. 

The  mucosa  is  lined  superficially  with  a  single  layer  of  columnar 
epithelium,  the  squamous  epithelium  of  the  oesophagus  having  ended 
abruptly  at  the  cardiac  orifice.  Besides  the  epithelial  layer  the 
mucosa  contains  the  basement  membrane,  the  stroma,  the  muscularis 
mucosce,  and  the  gastric  glands.  The  gastric  glands  are  of  two  kinds 
— peptic  and  pyloric.  The  peptic  glands  are  of  the  simple  tubular 
variety,  consisting  of  basement  membrane,  secreting  cells,  and  duct. 
The  mouth  of  the  duct  is  marked  by  a  slight  depression  upon  the 
surface  of  the  mucous  membrane.  These  glands  are  found  on  the 
cardiac  and  middle  thirds  of  the  stomach,  and  are  provided  with 


114:  NOKMAL  HISTOLOGY. 

acid  cells.  The  pyloric  glands  are  distributed  upon  the  pyloric  third 
of  the  stomach  and  are  of  the  compound  tubular  variety.  They  are 
not  provided  with  acid  cells.  They  have  a  wide  duct  which  leads 
to  the  narrow  lumens  of  the  tubular  branches.  The  stroma  consists 
of  connective  tissue  supplied  with  capillaries  and  lymphatics.  The 
muscularis  mucosw  consists  of  a  double  layer  of  smooth  muscle,  an 
inner  circular,  and  an  outer  longitudinal. 

The  sub-mucosa  is  composed  of  loosely-woven  bundles  of  elastic 
tissue,  containing  blood-vessels  and  nerves.  Upon  its  outer  surface 
there  are  alternate  elevations  and  depressions.  These  give  rise  to 
the  so-called  rugae  and  depressions  of  the  stomach  wall. 

The  muscular  coat  consists  of  an  inner  circular  layer  and  an 
outer  longitudinal  stratum  of  smooth  muscle.  At  the  cardiac  end 
there  is  also  a  middle  oblique  layer. 

The  serous  coat  consists  of  fibrous  tissue  and  elastic  fibres,  lined 
superficially  with  a  single  layer  of  endothelium. 

Laboratory  exercise  No.  34. — The  stomach.  Fix  in  corrosive  sublimate 
solution,  embed  in  celloidin,  and  stain  with  hsematoxylin  and  eosin, 
method  No.  8.  Use  H.  P.  and  L.  P.  First  demonstrate  the  four  coats; 
then  observe  the  internal  lining-  of  columnar  cells  with  their  basement 
membrane.  Locate  and  study  the  peptic  and  pyloric  glands.  Observe 
the  stroma  and  muscularis  mucosse;  also  distinguish  between  the  circu- 
lar and  longitudinal  muscle  layers.  How  does  the  serous  coat  differ  in 
appearance  from  the  sub-mucosa?  Drawings. 

THE  SMALL  INTESTINE. 

The  small  intestine  comprises  the  duodenum,  jejunum,  and  ileum. 
These  parts  differ  but  slightly  in  general  structure.  There  are  the 
four  characteristic  coats — mucosa,  sub-mucosa,  muscular  coat,  and 
serous  coat. 

The  mucosa  consists  of  the  following  structures:  (1)  A  single 
layer  of  columnar  epithelial  cells,  which  cover  the  surfaces  of  conical 
elevations  which  stud  the  intestine,  the  villi;  (2)  the  basement 
membrane,  which  supports  the  epithelium;  (3)  the  stroma,  or 
tunica  propria,  which  forms  conical  projections,  the  villi.  It  con- 
sists chiefly  of  connective  tissue.  Each  villus  is  supplied,  superfi- 
cially, with  a  capillary  network,  and  through  its  center  extends  a 
lacteal.  (4)  The  muscularis  mucosw  consists  of  a  longitudinal  layer 
with  occasional  circular  fibres  of  smooth  muscle. 


THE  ALIMENTARY  CANAL.  115 

The  sub-mucosa  consists  chiefly  of  fibro-elastic  bundles  and  pene- 
trating blood-vessels  and  nerves. 

The  muscular  coat  is  in  two  layers,  an  inner  circular  and  an  outer 
longitudinal,  separated  b}r  connective  tissue. 

The  serous  coat  consists  of  connective  tissue  and  endothelium. 

There  are  four  varieties  of  glands  which  occur  in  the  intestinal 
wall.  The  glands  of  Lieberkuhn  occur  in  the  mucosa  and  are  dis- 
tributed along  the  whole  course  of  the  small  and  large  intestine, 
being  found  between  the  villi.  They  are  simple  tubular  depressions 
provided  with  basement  membranes  and  secreting  cells.  The 
glands  of  Brunner  are  of  the  same  type  as  the  pyloric  glands  of  the 
stomach,  but  owing  to  repeated  division  they  have  more  the  appear- 
ance of  the  compound  sacular  than  of  the  tubular  variety.  They  are 
serous,  and  not  of  the  mucous  type.  They  occur  in  the  duodenum. 
The  solitary  glands  are  to  be  found  in  the  sub-mucous  coat  and  con- 
sist of  isolated  lymph  follicles.  They  occur  in  the  small  and  large 
intestines.  Peyer's  patches  are  compound  glands  of  the  racemose 
variety.  They  occur  in  the  mucosa  and  sub-mucosa.  They  should 
be  sought  in  the  small  intestine,  more  especially  in  the  ileum. 
Goblet  cells  are  of  frequent  occurrence  in  the  stomach  and  intestine. 
The  nerve  supply  of  the  alimentary  tract  is  from  the  cranial  and 
sympathetic  nerves. 

Laboratory  exercise  No.  35. — Small  intestine.  Fix  in  corrosive  sub- 
limate, embed  in  celloidin,  and  stain  with  haematoxylin  and  eosin.  Ex- 
amine with  L.  P.  and  H.  P.,  and  demonstrate  the  following  structures: 
Columnar  epithelium,  goblet  cells,  membrana  propria,  villi,  tunica 
propria,  capillaries,  glands  of  Lieberkuhn,  Brunner's  glands,  Peyer's 
patches,  solitary  glands,  muscularis  mucosse,  sub-mucosa,  circular  mus- 
cle layer,  longitudinal  muscle  layer,  serous  coat,  and  endothelium.  An 
injected  specimen  should  be  examined  to  demonstrate  the  capillary  net- 
work. Drawings. 

LARGE  INTESTINE. 

The  large  intestine  differs  chiefly  from  the  small  intestine  in 
possessing  thicker  walls  and  fewer  glands.  It  is  supplied  with  soli- 
tary follicles  and  the  glands  of  Lieberkuhn,  the  latter  containing 
many  goblet  cells.  There  are  the  usual  coats — mucosa,  sub-mucosa, 
muscular  coat,  and  serous  coat. 


116  NORMAL  HISTOLOGY. 

Laboratory  exercise  No.  36. — Large  intestine.  Fix  in  corrosive  sub- 
limate, embed  in  celloidin  or  paraffin,  and  stain  with  haBmatoxylin  and 
eosin,  method  No.  8.  Search  for  the  lacteal  in  the  center  of  a  villus. 
Demonstrate  the  different  coats  and  name  their  structural  elements. 
Find  the  glands  of  Lieberkuhn  and  solitary  follicles.  Drawings.  State 
the  functions  of  the  various  glands  of  the  alimentary  tract.  How  are 
capillaries  and  lacteals  distributed  ?  What  of  the  nerve  supply  and 
nerve  endings? 

(Esophagus. 


(Esophagus:  (a)  Mucosa;  (b)  Squamous  epithelium;  (c)  Membrana  propria; 
(d)  Stroma;  (e)  Muscularis  mucosae;  (f)  Sub-mucosa;  (g)  Connective  tissue;  (h) 
Glands;  (i)  Circular  muscle  layer;  ( j )  Longitudinal  muscle  layer;  (k)  Serous 
coat;  (1)  Endothelium. 

Stomach. 


Stomach:  (a)  Mucosa;  (b)  Columnar  epithelium;  (c)  Membrana  propria;  (d) 
Stroma;  (e)  Peptic  glands;  (f)  Pyloric  glands;  (g)  Muscularis  mucosae;  (h)  Sub- 
mucosa;  (i)  Connective  tissue;  (j  )  Bloodvessels;  (k)  Nerve;  (1)  Circular  muscle 
layer;  (m)  Longitudinal  muscle  layer;  (n)  Serous  coat. 


ALIMENTARY  TRACT. 


Small  Intestine. 


Small  Intestine:  (a)  Mucosa;  (b)  Columnar  epithelium;  (c)  Basement  mem- 
brane; (d)Stroma;  (e)Muscularismucosse;  (f)Villus;  (g)  Capillaries;  (b) Lacteal; 
(i)  Gland  of  Lieberkuhn;  (j)  Sub-mucosa:  (k)  Connective  tissue;  (1)  Brunner's 
gland;  (m)  Solitary  gland;  (n)  Peyer's  patch;  (o)  Circular  muscle  layer;  (p)  Lon- 
gitudinal muscle  layer;  (q)  Serous  coat. 

Large  Intestine. 


Large  Intestine:  (a)  Mucosa;  (b)  Columnar  epithelium;  (c)  Basement  mem- 
brane; (d)  Glands  of  Lieberkuhn;  (e)  Stroma;  (f)  Muscularis  mucosse;  (g)  Ves- 
sels; (h)  Sub-mucosa;  (i)  Solitary  gland ;  (j)  Peyer's  Patch;  (k)  Connective  tissue; 
(1)  Circular  muscle  layer;  (m)  Longitudinal  muscle  layer;  (n)  Serous  coat. 

[117] 


118  NORMAL  HISTOLOGY. 


CHAPTEE  XVI. 
THE  LIVER. 

The  liver  is  derived  from  the  epiderm  and  mesoderm.  It  is  de- 
veloped as  a  compound  tubular  gland,  but  afterwards  loses  that  type. 
Its  functions  are  secretion  and  excretion. 

OUTLINE  OF  THE  LIVER. 

Investment. 


Lobes.  f  Capsule  of  Glisson. 

Intralobular  vein. 
Interlobular  veins,  arteries,  and 


Lobules •{       bile  ducts. 

Hepatic  cells. 
Bile  capillaries. 
^  Blood  capillaries. 

f  Mucous  membrane. 

Gall  cyst <{   Muscular  coat. 

[_  Fibrous  coat. 

The  liver  is  invested  with  a  capsule  of  fibrous  connective  tissue, 
which  sends  prolongations  into  the  substance  of  the  organ,  produ- 
cing a  framework  for  the  support  of  the  vessels  and  cells.  The  or- 
gan is  composed  of  lobes,  and  these  are  subdivided  into  lobules. 
Each  lobule  is  surrounded  by  a  sheath  of  connective  tissue,  called 
the  capsule  of  Glisson.  This  capsule  contains  the  interlobular  veins 
(branches  of  the  portal  vein),  which  send  capillaries  into  the  sub- 
stance of  the  lobule.  These  converge  in  the  center  of  the  lobule  and 
form  the  intralobular  vein,  and  this  unites  with  others  to  form  sub- 
lobular  veins,  and  these,  in  turn,  form  the  hepatic  vein,  which  con- 
veys the  blood  from  the  liver.  Between  the  capillaries  are  to  be 
found  the  hepatic  cells,  devoid  of  cell  membranes  and  containing 
granular  protoplasm  and  one  or  two  nuclei.  The  bile-capillaries 
are  between  the  liver  cells  and  distinct  from  the  blood-capillaries. 
They  are  continuous  with  the  interlobular  bile-ducts,  the  latter  form- 
ing larger  ducts  which  are  lined  with  columnar  epithelium.  The 
lobule  also  contains  a  small  amount  of  areolar  tissue.  In  the  cap- 


THE  LIVER.  119 

snle  of  Glisson,  therefore,  are  to  be  found  the  interlobular  veins, 
arteries  (from  the  hepatic  artery),  and  bile-ducts.  A  thorough 
knowledge  of  the  liver  lobule  gives  the  key  to  a  knowledge  of  the 
whole  organ. 

The  gall  cyst,  which  receives  the  contents  of  the  hepatic  bile-duct, 
is  composed  of  mucous,  muscular,  and  fibrous  coats  The  larger 
bile-ducts  have  a  fibrous  adventitia  and  a  mucous  membrane  which, 
with  that  of  the  gall  cyst,  is  lined  with  columnar  epithelium. 

Laboratory  exercise  No.  37. — The  liver.  Harden  in  alcohol,  embed  in 
paraffin,  and  stain  with  haematoxylin  and  eosin.  Observe  upon  the  sur- 
face the  fibrous  investment  and  note  the  prolongations  of  its  structure 
into  the  interior.  Focus  upon  a  single  lobule  and  note  the  following- 
parts:  The  interlobular  vein,  centrally  located;  the  network  of  ra- 
diating blood  capillaries,  which  is  easily  demonstrated  in  injected  speci- 
mens; the  bile  capillaries  between  the  hepatic  cells,  which  receive  the 
bile  elaborated  within  the  lobule  and  convey  it  to  the  larger  bile  ducts; 
the  hepatic  cells,  noting  their  form  and  arrangement  and  granular 
appearance;  the  capsule  of  Glisson,  containing  bile  ducts  and  branches 
of  the  portal  vein  and  hepatic  artery.  Search  for  bile  ducts  and  the  gall 
cyst,  noting  their  structure.  Drawings. 

MEMORANDA. 


THE  LIVER. 


Liver  Structures. 


Liver:  (a)  Capsule;  (b)  Lobe:  (c)  Lobules;  (d)  Capsule  of  G-lisson;  (e)  Blood 
•vessels;  (f )  Hepatic  cells. 

A.  Liver  Lobule.  B.  Gall  Cyst. 


A.  Lobule:   (a)  Capsule  of  G-lisson;   (b)  Interlobular  vein;   (c)  Interlobular 
arteries;  (d)  Interlobular  bile  duct;   (e)  Capillary  network;   (f)  Bile  capillaries; 
(g)  Hepatic  Cells;  (h)  Intralobular  vein. 

B.  Gall  Cyst:   (a)  Mucous  coat;   (b)  Columnar  cells;   (c)  Muscular  coat;   (d) 
Fibrous  coat. 

[120] 


NORMAL  HISTOLOGY. 


121 


CHAPTER  XVII. 

TONGUE  AND  TEETH. 
I.  TONGUE. 

The  tongue  is  derived  from  the  epiderm  and  mesoderm.  It  con- 
sists chiefly  of  a  mucous  membrane  and  bundles  of  muscle  fibers  as- 
sociated with  connective  tissue.  It  is  the  organ  of  taste,  this  sense 
being  derived  especially  from  the  taste-buds  which  are  located  in 
the  squamous  epithelium  which  lines  its  surface. 

OUTLINE  OF  THE  TONGUE. 


Mucous  coat. 


f  Squamous  epithelium. 

Membrana  propria. 

Papillae    

Taste  buds. 
[  Furrows  and  ridges. 

Fibres. . . 


Filiform. 

Fungiform. 

Circumvallate. 


f  Branched. 
1  Striated. 


Muscular  tissue 


Adenoid  tissue 


Vertical. 

•{   Bundles •{   Transverse. 

Longitudinal. 
Septum  lingualae. 

Interfascicular  spaces       f  Connective  tissue. 

containing <   Fat. 

I  Glands. 
Reticulum. 


Lymphoid  cells. 
Blood  vessels,  lymphatics,  and  nerves. 

The  tongue  is  constituted  of  a  mucous  coat,  muscular  tissue,  ade- 
noid tissue,  blood-vessels,  lymphatics,  and  nerves.  The  mucous  coat 
contains  a  superficial  layer  of  stratified  squamous  epithelium.  With- 
in this  layer  are  located  the  taste-buds,  conical  bodies  which  are  the 
seat  of  the  sense  of  taste  and  are  found  upon  the  fungiform  and 
circumvallate  papillae,  and  in  the  epithelium  of  the  dorsum  and  sides 
of  the  tongue.  Beneath  the  squamous  epithelial  layer  is  the  mem* 


122  NORMAL  HISTOLOGY. 

brana  propria.  The  elevations  of  the  stroraa  of  the  mucosa  give  rise 
to  the  papillae.  These  are  of  three  forms,  filiform,  or  narrow ;  fungi- 
form,  or  club-shaped;  and  circumvallate,  or  broad  and  flat.  The 
circumvallate  papilla  are  confined  to  the  posterior  part  of  the  dor- 
sum.  The  fungiform  varieties  occur  upon  the  dorsum.  Often  sec- 
ondary papilla?  are  present. 

Glands  occur  in  the  stroma  and  are  of  the  mucous  and  serous 
types.  The  mucous  glands  are  of  the  compound  tubular  variety, 
and  occur  at  the  base  and  edges  of  the  tongue.  The  serous  glands 
are  of  the  saccular  form,  and  occur  near  the  circumvallate  papillae 
and  taste-buds. 

The  muscular  tissue  of  the  tongue  consists  of  striated  muscle 
fibres  arranged  in  bundles  which  run  vertically,  transversally,  and 
longitudinally.  The  spaces  between  the  bundles  are  filled  up  with 
connective  tissue,  fat-cells,  and  glands.  There  is  a  connective  tis- 
sue partition,  called  the  septum  lingualce,  which  passes  vertically 
through  the  middle  of  the  tongue,  dividing  the  muscular  tissue  into 
two  portions. 

The  adenoid  tissue  at  the  base  of  the  tongue  is  found  in  the 
crypts,  or  depressions,  of  the  mucosa,  and  consists  of  a  connective 
tissue  reticulum  and  lymphoid  ceils.  The  tongue  is  richly  supplied 
with  blood-vessels,  lymphatics,  and  nerves. 

Laboratory  exercise  No.  38. — The  tongue.  Harden  with  alcohol,  em- 
bed in  paraffin,  and  stain  with  carmine,  method  No.  3.  Study  first  the 
mucosa,  demonstrating  the  epithelial  layer,  basement  membrane,  tunica 
propria,  and  the  filiform,  fungiform,  and  circumvallate  papillae.  Make 
a  search  for  taste  buds.  Observe  the  loose  fibrous  structure  of  the 
tunica  propria  and  demonstrate,  if  possible,  mucous  and  serous  glands. 
Notice  the  disposition  of  the  bundles  of  striated  fibres.  Focus  upon  a 
fibre  with  H.  P.  and  demonstrate  its  striations.  In  the  inter-fascicular 
spaces  observe  connective  tissue  and  fat-cells.  A  section  prepared  from 
the  base  of  the  tongue  should  exhibit  adenoid  tissue  in  the  crypts  of  the 
mucosa.  Does  your  section  show  the  septum  lingualae?  Drawings. 

II.  THE  TEETH. 

The  teeth  are  derived  from  the  epiderm  and  mesoderm.  The  most 
important  structure  of  the  tooth  is  the  pericementum,  or  peridental 
membrane,  for  upon  its  healthy  action  the  condition  and  usefulness 


TONGUE  AND  TEETH.  123 

of  the  tooth  depend.  It  serves  to  hold  the  tooth  in  place,  as  well  as 
to  manufacture  the  cementum.  The  cavity  which  contains  the  tooth 
and  is  lined  by  the  pericernentum  is  called  the  alveolus.  The  layer 
produced  by  the  pericementum  and  covering  the  root  of  the  tooth 
is  the  cementum.  The  corresponding  layer  upon  the  crown  of  the 
tooth  is  the  enamel.  The  enamel  and  cementum  enclose  the  den- 
tine,  commonly  called  ivory.  In  the  cavity  of  the  tooth,  which  is 
surrounded  by  the  dentine,  is  the  pulp.  The  blood  and  nerve  supply 
of  the  tooth  is  conveyed  through  an  opening  at  the  extremity  of  each 
root.  A  single  nerve  fibre  enters  each  tooth  and  its  branches  follow 
the  course  of  the  blood-vessels. 

The  enamel  is  derived  from  the  epiderm ;  the  dentine  and  ce- 
mentum. from  the  mesoderm.  A  tooth  is  developed  from  the  dental 
ridge,  which  forms  the  enamel  organ,  and  from  the  dental  papilla, 
which  consists  of  mesodermic  connective  tissue.  The  latter  grows 
up  toward  the  enamel  organ,  so  that  the  two  are  in  contact.  The 
enamel  organ  produces  the  enamel,  and  the  dental  papilla  produces 
the  dentine. 

OUTLINE  OF  THE  TEETH. 


Alveolus. 
Pericementum  . 

(  Fibers. 
|  Fibroblasts. 
1  Cementoblasts. 
|  Osteoblasts. 
|  Osteoclasts. 
[Glands. 

Dentine 


f  Fibrous  reticulum. 

Matrix ] 

\  Calcareous  salts. 


Dentinal  tubules. 


fDentinal  sheaths. 


L  Dentinal  fibers. 
Interglobular  spaces. 
Schreger's  lines. 
Lines  of  Salter. 


C  Membrane  of  Nasmyth. 

Enamel <  Enamel  prisms. 

[  Stripes  of  Retzius. 

f  Lamellae. 

Cementum J  Lacunae. 

1  Canaliculi. 
[  Corpuscles. 


124  NORMAL  HISTOLOGY. 

f  Connective  tissue  matrix. 
-r,  ,  I  Stellate  and  spindle  cells. 

U1P 1  Odontoblasts. 

[  Blood  vessels  and  nerves. 

Pericementum. — The  structural  elements  of  this  membrane  are 
the  fibres,  the  fibroblasts,  the  cementoblasts,  the  osteoblasts,  osteo- 
clasts,  and  glands.  The  -fibres  are  of  the  white  fibrous  variety,  and 
their  chief  function  is  to  hold  the  tooth  in  position.  The  fibroblasts 
are  spindle-shaped  cells  which  occur  between  the  fibres.  The  osteo- 
blasts  are  the  bone  formers,  and  are  exactly  like  those  of  the  peri- 
osteum. The  osteodasts  are  the  giant  cells  which  have  the  power 
to  dissolve  calcareous  matter.  Cementoblasts  engage  in  the  forma- 
tion of  the  cementum. 

The  cementum. — This  covers  the  root  of  the  tooth  and  differs 
from  bone  in  having  no  Haversian  canals.  It  is  thin  at  the  neck, 
but  becomes  thicker  toward  the  extremity  of  the  root.  It  is  made 
up  of  lamellae,  lacunas,  cement  corpuscles,  and  canaliculi.  The 
canaliculi  are  supposed  to  communicate  with  the  dentinal  tubules. 

Enamel. — The  enamel  exhibits  the  membrane  of  Nasmyth,  the 
enamel  prisms,  and  the  stripes  of  Eetzius.  The  membrane  of  Nas- 
mytli  is  a  tough  epithelial  sheath  which  covers  the  crown  during  its 
earliest  development.  The  enamel  prisms  are  five  or  six-sided  rods, 
which  extend  out  perpendicularly  from  the  dentine.  When  enamel 
is  attacked  by  acids,  it  is  completely  dissolved,  which  is  not  true  of 
dentine  and  cementum. 

Dentine.. — Some  of  the  structures  of  dentine  are  the  dentinal 
tubules,  interglobular  spaces,  lines  of  Salter,  etc.  The  dentinal 
tubules  are  minute  canals,  which  extend  from  the  pulp  to  the  outer 
surface  of  the  dentine.  Each  tubule  consists  of  a  sheath  called  the 
sheath  of  Neumann,  within  which  is  a  dentinal  fibril,  a  prolonga- 
tion from  an  odontoblast  of  the  pulp.  The  lines  of  Salter  are  lines 
which  appear  in  dried  specimens,  and  are  probably  due  to  a  shrink- 
age of  the  tooth.  The  dentine  is  composed  of  twenty-eight  per  cent 
of  organic  matter  and  seventy- two  per  cent  of  inorganic  matter. 
The  interglobular  spaces  consist  of  uncalcified  portions  of  the  ma- 
trix. They  appear  as  irregular  spaces  and  are  sometimes  quite  abun- 
dant. 


TONGUE  AND  TEETH.  125 

The  pulp  — This  fills  the  cavity  of  the  tooth  within  the  dentine. 
It  consists  of  a  connective  tissue  matrix,  stellate  and  spindle  cells, 
round  cells,  and  odontoblasts.  The  outer  surface  of  the  pulp  is 
covered  with  a  layer  of  odontoblasts.  Most  of  the  cells  beneath  the 
odontoblasts  are  stellate  and  spindle-shaped.  The  protoplasmic 
processes  of  the  odontoblasts,  which  extend  into  the  dentinal  tubules, 
are  called  the  fibres  of  Tomes.  The  odontoblasts  are  directly  con- 
cerned'in  the  manufacture  of  dentine. 

Laboratory  exercise  No.  39.— The  teeth.  Decalcify  in  dilute  nitric 
acid,  harden  in  alcohol,  embed  in  celloidin,  and  stain  with  kaematoxylin. 
Examine  a  longitudinal  section  and  demonstrate  as  far  as  possible  the 
cementum  with  its  lamellae,  lacuna?,  cement  corpuscles,  and  canaliculi; 
also  the  dentine,  exhibiting  dentinal  tubules,  sheath  of  Neumann,  den- 
tinal fibrils,  and  inter-globular  spaces;  also  the  enamel,  showing  the 
enamel  prisms,  matrix,  and  membrane  of  Nasmyth.  Drawings.  The 
demonstrations  of  enamel  must  be  made  from  dry  sections,  as  acids 
completely  dissolve  this  structure. 

MEMORANDA. 


TONGUE  AND  TEETH. 


Tongue. 


Tongue:  (a)  Mucous  coat;  (b)  Squamous  epithelium;  (c)  Taste  buds;  (d) 
Membrana  propria;  (e)  Filiform  papilla;  (f)  Fungiform  papilla;  (g)  Circumvallate 
papilla;  (h)  Submucous  tissue;  (i)  Muscular  tissue;  (j)  Vertical  fibers;  (^Trans- 
verse fibers;  (1)  Longitudinal  fibers;  (m)  Septum  lingualae;  (n)  Interfascicular 
connective  tissue;  (o)  Fat  cells;  (p)  Adenoid  tissue. 

Teeth. 


Teeth:  (a)  Pericementum— showing  fibers,  cementoblasts,  etc.;  (b)  Cementum 
—showing  lamella,  lacunae,  canaliculi,  and  corpuscles;  (c)  Enamel  —  exhibiting 
enamel  prisms;  (d)  Dentine;  (e)  Dentinal  tubule  —  showing  dentinal  sheath  and 
fibers;  ( f )  Interglobular  spaces;  (g)  Pulp;  (h)  Odontoblasts;  (i)  Stellate  cells;  (j) 
Spindle  cells. 
[126] 


NORMAL  HISTOLOGY.  127 


CHAPTEE  XVIII. 

THE  RESPIRATORY  SYSTEM. 

The  respiratory  system  includes  the  air  passages  of  the  nose, 
mouth  and  pharynx,  and  the  epiglottis,  larynx,  trachea,  bronchi, 
lungs,  and  pleura.  Its  structures  are  derived  wholly  from  the  epi- 
derm  and  mesoderm.  Its  nerve  supply  is  from  the  cerebro-spinal 
and  sympathetic  systems. 

Epiglottis. — This  structure  consists  chiefly  of  yellow  elastic  car- 
tilage. Its  mucosa  possesses  many  taste-buds  and  leucocytes. 

Larynx. — The  thyroid,  cricoid,  and  arytenoid  cartilages  make  up 
the  bulk  of  the  larynx.  These  are  united  by  fibrous  tissue  and  liga- 
mentous  membranes  and  are  covered  internally  with  a  mucosa,  and 
externally  with  fibrous  tissue. 

THE  TRACHEA. 

The  trachea  comprises  a  mucosa,  a  sub-mucosa,  and  fibrous  coat. 
It  is  largely  a  mesodermic  structure. 

OUTLINE  OF  THE  TRACHEA. 


f  Ciliated  epithelium. 
1   M 


Mucosa <   Membrana  propria.  f  Inner  layer. 

^  Tunica  propria •{ 

[  Outer  layer. 
f  Connective  tissue. 

Sub-mucosa 1   glood  vessels?  iymphatics,  and  nerves. 

Smooth  muscle. 

f  Perichondrium. 

Hyaline  cartilage <  Matrix. 

Fibrous  coat <{  [  Cells. 

Connective  tissue. 

The  mucosa  presents  a  superficial  layer  of  stratified  ciliated  epi- 
thelium supported  by  a  basement  membrane  and  a  tunica  propria 
which  possesses  a  large  amount  of  elastic  tissue  and  is  disposed  in 
two  layers :  An  inner  layer  of  loose  fibrous  tissue  containing  elastic 
fibres,  nerve  fibres,  etc.,  and  an  outer  layer,  consisting  of  a  dense 
network  of  longitudinal  elastic  fibres.  Of  the  epithelium,  only  the 


128  NORMAL  HISTOLOGY. 

outer  layer  of  cells  possesses  cilia.  Among  these  occur  the  goblet 
cells. 

The  sub-mucosa  is  made  up  of  loose  connective  tissue  containing 
glands,  blood-vessels,  lymphatics,  and  nerves. 

The  fibrous  coat  invests  the  outer  surface  of  the  trachea  and 
has  embedded  in  its  tissue  the  incomplete  rings  of  hyaline  cartilage. 
These  rings  in  transverse  section  appear  fusiform  in  outline,  extend 
over  three-fourths,  or  less,  of  the  circumference,  overlap  by  their 
edges,  and  exhibit  pcrichondrium,  matrix,  lacunas,  and  cells.  At- 
tached to  the  perichondrlum  upon  the  inner  surfaces  of  the  cartilage 
are  transverse  bundles  of  smooth  muscle,  while  across  the  intervals 
between  the  rings  are  other  bundles,  the  whole  contrivance  serving 
to  contract  the  tube.  There  are  but  few  longitudinal  muscular  bun- 
dles. 

Laboratory  exercise  No.  40.— Trachea.  Fix  with  ehromic  acid,  harden 
with  alcohol,  embed  in  cello idin,  and  stain  with  hsematoxylin,  method 
No.  7.  Make  out  the  structures  of  the  mucosa,  observing  especially  the 
layer  of  ciliated  epithelium  containing*  a  few  goblet  cells,  the  membraria 
propria,  and  the  two  layers  of  the  tunica  propria.  Search  for  glands, 
blood-vessels,  etc.,  in  the  sub-mucosa.  Study  the  form  and  structure  of 
the  hyaline  cartilage  in  the  fibrous  layer.  Note  the  disposition  of  the 
bundles  of  smooth  muscle.  Demonstrate  the  loose  areolar  tissue  which 
unites  the  fibrous  coat  to  adjacent  structures.  Drawings. 

The  bronchi.  — These  do  not  differ  materially  in  structure  from 
the  trachea.  As  the  bronchial  tubes  decrease  in  size  there  are  cer- 
tain modifications  in  structure,  such  as:  (1)  The  epithelium  be- 
comes reduced  until  in  the  smallest  tubes  there  is  but  a  single  layer 
of  ciliated  cells.  (2)  The  elastic  tissue  disappears  from  the  mu- 
cosa and  is  replaced  by  a  smooth  muscle  layer  that  corresponds  to 
the  muscularis  mucosae.  (3)  The  cartilage  gradually  decreases  and 
totally  disappears  in  the  terminal  bronchioles. 

THE  LUNGS. 

The  lungs  are  derived  chiefly  from  the  mesoderm.  They  resem- 
ble in  structure  racemose  glands.  Their  nerve  supply  is  received 
from  the  central  and  sympathetic  systems. 


THE  RESPIRATORY  SYSTEM. 


129 


OUTLINE  OF  THE  LUNGS. 


r  Bronchial  tubes. 

Ducts •{   Bronchioles. 

Alveolar  ducts. 


Spaces    ^ 

'  Infundibula. 

.  Alveoli. 
r  Lobes 

i 

Lobules  <j 

Infundib- 
ular septa. 
Alveolar 

Pulmonary  paren- 
chyma .  .                   .  4 

i 

Interlobular 

walls. 

Pleura 


L  Blood  vessels,  lymphatics,  and  nerves. 

("  Endothelium. 

<(   Connective  tissue. 

[  Subpleural  tissue. 


The  hings  are  invested  with  a  connective  tissue  sheath,  the  pleura, 
which  is  made  up  of  endothelium,  a  connective  tissue  matrix,  con- 
sisting of  fibrous  tissue  bundles  and  elastic  fibres,  and  the  sub- 
pleural  tissue,  composed  of  areolar  tissue  and  elastic  fibres.  Each 
lung  is  comprised  of  lobes ;  each  lobe,  of  lobules ;  and  each  lobule  con- 
sists of  ducts,  air  spaces,  and  pulmonary  parenchyma. 

The  smaller  bronchial  tubes,  or  bronchioles,  become  the  terminal 
bronchioles  when  their  diameter  does  not  exceed  1  mm.  They  end 
in  the  alveolar  ducts,  which  are  lined  with  alveoli,  or  air  sacs;  and 
extending  from  these  ducts  are  irregular  cavities,  the  infundibula, 
which  are  also  studded  with  alveoli. 

The  pulmonary  parenchyma  comprises  the  walls  of  blood-vessels, 
lymphatics,  bronchioles,  and  alveolar  ducts,  the  alveolar  walls,  and 
the  infundibular  septa.  A  bronchiole  may  be  distinguished  from 
a  blood-vessel  under  the  microscope  by  the  crenated  appearance  of 
its  inner  surface.  The  terminal  bronchioles  are  lined  with  a  single 
layer  of  ciliated  epithelial  cells,  and  their  walls  consist  of  elastic 
fibres  and  smooth  muscle.  Each  alveolar  duct  is  lined  with  cu- 
boidal  cells,  and  its  wall  otherwise  resembles  that  of  a  bronchiole, 
but  is  much  thinner.  The  wall  of  an  alveolus  is  lined  with  simple 
squamons  epithelium  and  comprises  also  a  connective  tissue  frame- 
work and  a  dense  capillary  network.  The  connective  tissue  frame- 


130  NORMAL  HISTOLOGY. 

work  of  elastic  fibres  surrounds  each  air  sac  and  forms  the  septum 
between  adjoining  alveoli. 

Laboratory  exercise  No.  41.— Lungs.  Fix  in  chromic  acid,  dehydrate 
with  alcohol,  embed  in  celloidin,  and  stain  with  lithium  carmine, 
method  No.  4.  Make  a  careful  study  of  the  structures  above  named. 
Demonstrate  arteries,  veins,  and  bronchioles.  Distinguish  between  an 
alveolus  and  an  infundibulum.  With  H.  P.,  make  out  the  structure  of 
different  portions  of  the  pulmonary  parenchyma.  Drawings. 

Trachea. 


Trachea:  (a)  Mucous  coat;  (b)  Ciliated  epithelium;  (c)  Membrana  propria;  (d) 
Tunica  propria;  (e)  Submucous  tissue ;  (f)  Hyaline  cartilage— showing  perichon- 
drium,  matrix,  and  cells;  (g)  Muscular  coat;  (h)  Fibrous 'coat;  (i)  Serous  coat. 

Lungs. 


Lungs:  (a)  Bronchiole;  (b)  Alveolar  duct;  (c)  Alveolus;  (d)  Infundibulum;  (e) 
Infundibular  septa;  (f) Alveolar  wall;  (g)  Artery;  (h)  Vein;  (i)  Pleura. 


NORMAL  HISTOLOGY. 


131 


CHAPTER  XIX. 

THE  URINARY  TRACT. 

The  organs  of  the  urinary  tract  are  the  kidney,  ureters,  bladder, 
and  urethra.  Their  tissues  are  derived  from  the  epiderm  and  meso- 
derm.  The  nervous  supply  is  obtained  from  the  cerebro-spinal  and 
s}onpathetic  systems. 

THE  KIDNEY. 

The  kidney  is  one  of  the  parenchyinatous  organs  of  the  body,  il- 
lustrating a  compound  tubular  gland  and  functioning  as  an  organ 
of  excretion.  The  urine  is  secreted  from  the  blood  in  the  Mal- 
pighian  bodies  and  uriniferous  tubules,  and  contains  the  products 
of  destructive  metabolism. 


OUTLINE  OF  THE  KIDNEY. 


Cortex 


Medulla. 


Sinus  . . 


Capsule. 

Muscular 
coat. 

Malpighian       i 
bodv  .  .       .  .  < 

Labyrinth.  .  « 

Column  of 
Bertini. 

Medullary 
rays. 

Blood 

vessels. 

^  Urineriferous 
tubule  • 

Stroma. 

Malpighian 
pyramids.  < 

'  Base. 

Tubules. 

Hilum. 
Pelvis. 
Calices. 


Papilla. 


(  Capsule  of  Bowman. 
1  Glomerulus. 

Neck. 

Lumen. 

Proximal  convoluted  tubule. 

Spiral  tubule. 

Descending  limb  of  Henle's 

loop. 

Henle's  loop. 
Ascending  limb  of  Henle's 

loop. 

Irregular  tubule. 
Distal  convoluted  tubule. 
Arched  collecting  tubule. 
Straight  collecting  tubule. 
Excretory  duct,  or  tube  of 

Bellini. 


The  outside  investment  of  the  kidney  is  a  capsule  of  fibrous  tis- 
sue, within  which  is  a  thin  layer  of  smooth  muscle.   The  cortex  of 


132  NOKMAL  HISTOLOGY. 

the  kidney  occupies  the  outer  one-third  and  contains  the  labyrinth, 
medullary  rays,  and  blood-vessels.  The  labyrinth  comprises  the  Mal- 
pighian  bodies  and  uriniferons  tubules.  The  Malpighian  body  con- 
sists of  the  capsule  of  Bowman  and  the  glomerulus.  The  capsule 
is  lined  with  a  single  layer  of  flattened  epithelial  cells.  The  glom- 
erulus consists  of  a  coil  of  capillaries.  Entering  each  capsule  is  an 
afferent  artery,  and  passing  from  it  an  efferent  vein.  The  urinif- 
erous  tubule,  which  proceeds  from  the  pole  of  the  capsule  opposite 
the  entrance  of  the  artery,  comprises  the  following  parts :  (1)  The 
neck,  lined  with  low  cuboidal  cells;  (2)  the  convoluted  tubule, 
which  is  lined  with  low  columnar  cells ;  (3)  the  spiral  tubule,  similar 
in  structure  to  the  convoluted  portion;  (4)  the  descending  limb  of 
Henle's  loop,  lined  with  simple  squamous  epithelium;  (5)  Henle's 
loop,  composed  of  polyhedral  cells  with  flattened  nuclei;  (6)  the 
ascending  limb  of  Henle's  loop,  with  structure  resembling  that  of 
the  loop;  (7)  the  irregular  tubule,  composed  of  striated  epithe- 
lium; (8)  the  distal  convoluted  tubule,  consisting  of  granular 
epithelium;  (9)  the  arched  collecting  tubule,  lined  with  low  cu- 
boidal cells;  (10)  the  straight  collecting  tubule,  which  possesses 
columnar  cells;  (11)  the  excretory  duct,  or  tube  of  Bellini,  which 
is  lined  with  tall  columnar  epithelial  cells. 

The  columns  of  Bertini  constitute  the  masses  of  the  kidney  be- 
tween the  Malpighian  pyramids;  they  extend  to  the  pelvis. 

The  medullary  rays  are  tapering  bundles  of  straight  tubules, 
which  extend  from  the  medulla  into  the  cortex. 

The  blood-vessels  of  the  kidney  enter  at  the  hilum.  The  renal 
artery  passes  through  the  sinus,  gives  off  twigs,  which  extend 
through  the  columns  of  Bertini  to  the  cortex,  and  enters  the  Mal- 
pighian body  by  the  afferent  artery,  which  splits  up  into  capillaries 
to  form  the  glomerulus ;  these  unite  to  form  the  efferent  vein,  which 
unites  with  similar  veins  to  form  the  interlobular  vein. 

The  stroma  constitutes  the  connective  tissue  structures,  which  in- 
vest the  blood-vessels  and  tubules. 

The  medulla  is  composed  of  from  eight  to  twenty  Malpighian  pyr- 
amids. Each  pyramid  is  made  up  of  tubules,  its  base  corresponding 
with  the  line  of  juncture  between  the  medulla  and  cortex;  and  its 


THE  URINARY  TRACT.  133 

apex  rests  upon  the  sinus,  and  by  its  encroachment  upon  this  .struc- 
ture produces  a  papilla.  The  base  of  the  pyramid  is  capped  by  the 
cortical  arch. 

The  sinus  is  the  cavity  at  the  basal  portion  of  the  kidney.  The 
opening  into  this  cavity  is  the  hilum.  The  cavity  itself  is  formed 
by  a  union  of  the  excretory  ducts,  thus  producing  one  large  lumen, 
and  is  invested  with  a  coat  which  is  continuous  with  the  capsule 
of  the  kidney,  and  within  this  is  the  wall,  which  is  continuous  with 
that  of  the  ureter.  The  space  within  this  capsule  is  the  pelvis. 

THE  URETER. 

This  structure  is  composed  of  three  coats — mucous,  muscular, 
and  fibrous.  The  mucous  membrane  is  lined  with  the  so-called  tran- 
sitional epithelium,  which  consists  of  few  layers,  the  deeper  layers 
being  columnar,  and  those  next  the  lumen,  squamous. 

THE  BLADDER. 

The  bladder  has  three  coats — mucous,  muscular,  and  fibrous.  The 
mucous  coat  is  lined  with  stratified  transitional  epithelium,  the  cells 
presenting  considerable  irregularity  in  shape,  and  often  possesssing 
more  than  one  nucleus. 

THE  URETHRA. 

The  urethra  consists  of  mucous  and  muscular  coats.  The  mucous 
coat  of  the  female  urethra  is  lined  throughout  with  stratified  squa- 
mous epithelium.  In  the  male  urethra  the  prostatic  portion  is  lined 
with  transitional  epithelium,  the  intermediate  part  with  stratified 
columnar  cells,  while  these  are  succeeded  in  the  penile  portion  by 
simple  columnar  cells. 

Laboratory  exercise  No.  42. — The  kidney.  Harden  with  alcohol,  em- 
bed in  paraffin,  and  stain  with  haematoxylin  and  eosin.  Upon  the  onter 
surface  of  your  section  observe  the  capsule,  and  beneath  this  a  delicate 
layer  of  smooth  muscle.  Distinguish  between  the  cortex  and  medulla. 
Observe  the  Malpighian  pyramids  of  the  medulla.  Their  apices  form 
the  papillae,  and  their  bases  extend  toward  the  periphery.  What  ele- 
ments enter  into  their  structure?  The  spherical,  deeply-stained  masses 
in  the  medulla  are  the  Malpighian  bodies.  Demonstrate  the  capsule  of 
Bowman  and  glomerulus;  also  the  structure  of  a  tubule,  noting  its 
basement  membrane,  epithelial  cells,  and  lumen.  Make  a  study  of 
other  structures  enumerated  in  the  outline  of  this  organ.  Drawings. 


KIDNEY. 


Cortex  and  Medulla. 


Kidney:  A.  Cortex:  (a)  Capsule;  (b)  Muscular  layer;  (c)  Labyrinth;  (d)  Malpighian  body; 
(e)  Capsule  of  Bowman;  (f)  Glomerulus;  (g)  TJriniferous  tubule;  (h)  Column  of  Bertini;  (i) 
Medullary  ray;  ( j )  Blood  vessels;  (k)  Stroma. 

B,  Medulla:  (1)  Malpighian  pyramid;  (m)  Base;  (n)  Apex,  or  papilla;  (o)  Tubules;  (p) 
Sinus — exhibiting  hilum,  pelvis,  and  calices, 

Uriniferous  Tubule. 


TJriniferous  Tubule:    (a)  Neck;    (b)  Lumen;    (c)  Proximal  convoluted  tubule;   (d)   Spiral 
tubule;  (e)  Descending  limb  of  Henle's  loop;    (f )  Henle's  loop;    (g)  Ascending  limb  of  Henle's 
loop;    (h)  Irregular  tubule;    (i)  Distal  convoluted  tubule;    (j)  Arched  collecting  tubule;    (k) 
Straight  collecting  tubule;  (1)  Excretory  duct,  or  tube  of  Bellini. 
[134] 


NORMAL  HISTOLOGY.  135 


CHAPTEE  XX 
THE  GENITAL  ORGANS. 

The  reproductive  organs  are  derived  from  the  epiderm  and  meso- 
derm.  As  among  many  plants,  they  exhibit  sexual  characteristics. 
The  function  of  the  male  organs  is  the  production  of  semen,  which 
contains  the  spermatozoa,  or  male  elements.  The  female  organs 
produce  the  ova,  female  elements,  as  well  as  contribute  to  the  de- 
velopment of  the  fertilized  ova  and  the  resulting  embryos. 

I.  MALE  REPRODUCTIVE  ORGANS. 

The  male  reproductive  organs  comprise  the  testis,  prostate  gland, 
Cowper's  glands,  and  penis. 

THE  TESTIS. 

The  testis  is  a  compound  tubular  gland  whose  function  is  to  pro- 
duce the  spermatazoa.  It  is  enveloped  in  a  fibrous  capsule  and  is 
divided  into  lobules. 

OUTLINE  OF  THE  TESTIS. 


Tunica  vaginalis. 

Tunics •{   Tunica  albuginea. 

Tunica  vasculosa. 

Mediastinum,  or  corpus  Hig-hmori. 

Septa.  C  Parietal  cells. 

(Convoluted  tubul^ !   Mother  cells. 

Tubili  recti.  ]   Spermatoblasts. 

Rete  testis.  [  Spermatozoa. 

f  Vasa  efferentia. 
j   Coni  vasculosi. 
Vessels •{   Tube  of  epididymus. 

Vas  deferens. 

Vas  aberrans. 

The  testis  is  suspended  in  a  sac,  the  scrotum,  and  is  immediately 
invested  with  three  coats — the  tunica  vaginalis,  or  serous  coat,  de- 
rived from  the  peritoneum;  the  tunica  albuginea,  or  dense  fibrous 
coat,  which  on  the  posterior  border  of  the  testis  forms  by  an  inver- 


136  NOKMAL  HISTOLOGY. 

sion  of  the  capsule  a  much  thickened  mass,  the  mediastinum,  or 
corpus  Highrnori;  and  the  tunica  vasculosa,  containing  a  plexus  of 
blood-vessels  invested  by  delicate  areolar  tissue.  The  septa,  which 
extend  from  the  mediastinum  to  the  tunica  albuginea  on  the  oppo- 
site side,  thus  dividing  the  testis  into  lobules,  are  continuous  with 
tunica  vasculosa.  Each  lobule  is  composed  of  tubules  of  three  kinds 
— convoluted  tubules,  tubuli  recti,  and  those  of  the  rete  testis.  The 
convoluted  tubule  consists  of  a  basement  membrane  lined  with  the 
sustentacular  cells,  or  parietal  layer.  Just  within  this  layer  are  the 
mother  cells,  which  grow  into  large  cells  and  multiply  by  mitosis. 
Then  follow  the  daughter  cells,  or  spermatoblasts.  Within  these 
are  to  be  found  the  spermatozoa.  These  tubules  are  supported  by 
connective  tissue  derived  from  the  septa,  arc  provided  with  blind 
extremities,  and  each  has  a  membrana  propria.  The  tubuli  recti 
comprise  the  straight  tubules  formed  by  the  union  of  the  convoluted 
tubules  near  the  apex  of  the  pyramidal  lobule,  and  possess  a  base- 
ment membrane  lined  with  columnar  cells.  The  rete  testis  consists 
of  anastomosing  tubules  forming  a  network  within  the  mediastinum. 

The  vessels,  or  ducts,  associated  with  the  tubules  are  the  vasa  ef- 
ferentia,  coni  vasculosi,  epididymis,  vas  deferens,  and  vas  aberrans. 
The  tubules  of  the  rete  testis  emerge  from  the  mediastinum  in  fif- 
teen or  twenty  ducts,  the  vasa  efferentia.  These  soon  become  con- 
voluted in  their  course,  forming  conical  masses,  the  coni  vasculosi, 
which  together  constitute  the  head  of  the  epididymis,  or  globus 
major.  The  tube  of  the  epididymis  is  formed  by  the  union  of  the 
ducts  of  the  coni  vasculosi.  This  tube  is  greatly  convoluted,  and 
when  unraveled  measures  upward  of  twenty  feet.  The  vas  aber- 
rans is  a  narrow  tube,  which  extends  from  the  lower  part  of  the 
tube  of  the  epididymis  and  is  closed  by  a  blind  extremity.  The  vas 
deferens  is  continuous  with  the  epididymis,  and  is  the  excretory  duct 
of  the  testis.  It  consists  of  three  coats — epithelial,  muscular,  and 
mucous. 

THE  PROSTATE  GLAND.— This  is  composed  largely  of 
smooth  muscle,  within  which  are  a  number  of  tubular  glands,  whose 
ducts  open  into  the  urethra.  The  fibrous  capsule  is  thin,  but  firm. 

COWPER'S  GLANDS. — These   are  two  in  number,   and  in 


THE  GENITAL  ORGANS. 


137 


structure  are  of  the  compound  tubular  variety.    The  excretory  duct 
from  each  opens  into  the  urethra. 

THE  PENIS. — The  two  corpora  cavernosa  and  the  corpus 
spongiosum  enter  into  the  structure  of  this  organ.  The  corpus 
cavernosum  consists  of  a  fibrous  sheath,  trabeculae  of  connective  tis- 
sue, and  smooth  muscle.  The  corpus  spongiosum  resembles  in  struc- 
ture the  corpus  cavernosum,  but  its  connective  tissue  is  more  deli- 
cate. 

Laboratory  exercise  No.  43. — Testis.  Harden  in  alcohol,  embed  in 
paraffin,  and  stain  with  lithium  carmine,  method  No.  3.  Demonstrate 
from  your  section  the  investing  tunics  (vaginalis,  albuginea,  and  vascu- 
losa),  lobules,  septa,  interlobular  connective  tissue,  parietal  cells, 
mother  cells,  spermatoblasts,  and  spermatozoa.  Drawings. 

II.  FEMALE  REPRODUCTIVE  ORGANS. 

The  female  reproductive  organs  are  the  ovary,  parovarium,  Fal- 
lopian tubes,  uterus,  vagina,  genitalia,  and  mammary  glands 

THE  OVARY. 

The  ovaries  correspond  to  the  testes,  are  oval -shaped,  and  are 
situated  one  on  each  side  of  the  uterus.  The  following  outline  ex- 
hibits their  structure : 


OUTLINE  OF  THE  OVARY. 


Cortex  . . 


Medulla. . 


{ Tunica  albuginea. 


Strom  a. 

Graafian  follicles.  \ 


f  Theca  folliculi. 
Membrana  granulosa. 
Discus  proligerus. 


Corpus  luteum. 
Stroma. 
Blood  vessels. 


f  Zona  pellucida. 

I  Vitelline  membrane. 

t  Ovum \  Vitellus. 

I  Germinal  vesicle. 
[  Germinal  spot. 


The  tunica  albuginea  is  a  serous  coat  derived  from  the  peri- 
toneum. The  cortex  includes  the  outer  one-third  of  the  ovary ;  and 
the  medulla,  the  inner  two-thirds.  The  stroma  is  the  connective  tis- 
sue ground  substance.  It  contains  numerous  spindle-cells  and  occurs 
in  both  medulla  and  cortex.  The  characteristic  structures  of  the 


138  NORMAL  HISTOLOGY. 

cortex  are  the  Graafian  follicles,  each  of  which  consists  of  the  theca 
folliculi,  composed  of  an  outer  and  inner  coat;  the  membrana  granu- 
losa,  comprising  several  layers  of  polyhedral  cells;  the  discus  pro- 
ligerus,  the  zone  of  cells  surrounding  the  ovum ;  and  the  ovum,  com- 
prising the  zona  pellucida,  an  investing  memhrane;  vitelline  mem- 
brane, the  cell-wall  of  the  ovum;  vitellus,  the  protoplasm  of  the  ovum, 
which  occupies  the  space  between  the  vitelline  membrane  and  the 
nucleus;  germinal  vesicle,  which  corresponds  to  the  nucleus;  and 
the  germinal  spot,  or  nucleolus. 

The  number  of  Graafian  follicles  in  the  two  ovaries  of  a  child 
is  estimated  to  be  70,000.  The  liquid  substance  within  the  follicle 
is  the  liquor  folliculi.  When  the  ovum  is  ripe  it  escapes  by  the 
bursting  of  the  wall  of  the  follicle,  which  has  gradually  approached 
the  surface  of  the  ovary.  This  makes  it  possible  for  the  ovum  to 
reach  the  outside  of  the  ovary,  and  pass  thence  to  the  Fallopian 
tube.  The  ovum  and  Graafian  f pllicle  are  developed  from  the  germ 
epithelium  upon  the  surface  of  the  ovary.  As  they  develop,  they 
gradually  pass  into  the  deeper  portion  of  the  cortex.  Upon  the 
escape  of  the  ovum,  the  ruptured  follicle  becomes  filled  with  poly- 
hedral cells,  which  are  penetrated  by  capillaries,  and  this  stage  is 
the  corpus  luteum. 

The  medulla  comprises  the  connective  tissue  stroma  and  blood- 
vessels. 

THE  PAROVARIUMisof  foetal  origin,  and  is  a  remnant  of 
the  Wolffian  body. 

THE  FALLOPIAN  tubes,  or  oviducts,  convey  the  ova  from 
the  ovary  to  the  uterus.  Each  tube  is  composed  of  three  coats — (1) 
the  mucous  coat,  comprising  a  single  layer  of  ciliated  epithelial  cells, 
a  tunica  propria  of  connective  tissue,  muscularis  mucosa?,  and  a 
small  amount  of  sub-mucous  tissue;  (2)  muscular  coat,  comprising 
circular  and  longitudinal  layers;  (3)  serous  coat,  derived  from  the 
peritoneum,  and  composed  of  loose  bundles  of  connective  tissue. 

THE  UTERUS. — This  is  a  continuation  of  the  Fallopian  tubes 
and  presents  three  coats — mucous,  muscular,  and  serous.  The  mu- 
cous coat  consists  of  a  fibrous  tunica  propria  and  a  simple  layer 
of  ciliated  epithelium.  Toward  the  cervical  end,  however,  the  mu- 


THE  GENITAL  ORGANS.  139 

cosa  is  thicker,  is  beset  with  papillae,,  and  its  surface  is  lined  with 
stratified  squamous  epithelium.  The  muscular  coat  is  dense  and  ia 
disposed  in  three  layers — inner,  middle,  and  outer — with  an  inter- 
mingling of  blood-vessels,  nerves,  lymphatics,  and  areolar  tissue. 

THE  VAGINA. — This  structure  possesses  a  mucosa,  sub-mucosa. 
and  muscular  and  serous  coats.  The  mucosa  is  studded  with  papil- 
lae, and  is  lined  with  stratified  squamous  epithelium ;  the  sub-mucosa 
consists  of  fibrous  bundles  and  elastic  fibres;  the  muscular  coat  is 
in  two  layers;  the  serous  coat  comprises  elastic  fibres  and  endo- 
thelium. 

The  mammary  glands  are  sebaceous  racemose  glands,  consisting 
of  lobes,  lobules,  and  acini,  with  ducts,  connective  tissue,  and  areolar 
and  adipose  tissues. 

Laboratory  exercise  No.  44. — The  ovary.  Harden  in  alcohol,  embed 
in  paraffin,  and  stain  with  haematoxylin  and  eosin.  Demonstrate  the 
following-:  Cortex,  composed  of  tunica  albuginea,  stroma,  Graafian  folli- 
cles, and  corpus  luteum;  the  medulla,  consisting1  of  the  stroma  and 
blood-vessels.  Make  a  study  of  a  Graafian  follicle,  noting  the  theca 
folliculi,  membrana  granulosa,  discus  proligerus,  and  ovum.  Focus  with 
H.  P.  upon  a  ripe  ovum  and  observe  the  vitelline  membrane,  vitellus, 
germinal  vesicle,  and  germinal  spot.  Drawings. 

Laboratory  exercise  No.  45. — Fallopian  tube  and  uterus.  These  may 
be  hardened  in  alcohol,  embedded  in  paraffin,  and  stained  with  lithium 
carmine,  method  No.  3.  Make  out  (and  illustrate  in  your  diagrams)  four 
characteristic  differences  between  these  organs.  How  are  the  cilia  dis- 
posed? 

MEMORANDA. 


GENITAL  ORGANS. 


A.  The  Testis.  B.  The  Ovary. 


A.  Testis:   (a)  Tunica  albuginea;  (b)  Mediastinum;  (c)  Septa;  (d)  Lobules;  (e)  Convoluted 
tubule;  (f )  Parietal  cells;  (g)  Mother  cells;  (h)  Spermatoblasts;  (i)  Spermatozoa;  (j)  Basement 
membrane;  (k)  Tubuli  recti;  (1)  Rete  testis. 

B.  Ovary:    (a)  Tunica  albuginea;    (b)  Medulla,  containing  stroma  and  blood  vessels:    (c) 
Cortex;    (d)  Stroma;   (e)  Graafian  follicle;    (f)  Theca  folliculi;    (g)  Membrana  granulosa;   (h) 
Discus  proligerus;  (i)  Ovum;  (j)  Corpus  luteum, 

Ovum:  (a)  Zona  pellucida;  (b)  Vitelline  membrane;  (c)  Vitellus;  (d)  Germinal  vesicle;  (e) 
Germinal  spot. 

A.  Fallopian  Tube.  B.  Uterus. 


A.  Fallopian  Tube:  (a)  Mucosa;  (b)  Ciliated  epithelium;  (c)  Tunica  propria;  (d)  Muscularis 
mucosae;  (e)  Submucosa;  (f )  Circular  muscle  layer;  (g)  Longitudinal  muscle  layer;  (h)  Serous 
coat. 

B.  Uterus:  (a)  Ciliated  or  squamous  epithelium;  (b)  Tunica  propria;  (c)  Uterine  glands;  (d) 
Folds;  (e)  Muscular  coat;  (f)  Serous  coat;  (g)  Endothelium. 

[140] 


NORMAL  HISTOLOGY.  141 


CHAPTEE  XXI. 
EYE,  EAR,  AND  NOSE. 

The  organs  of  special  sense  are  developed  from  the  epiderm. 
Their  nervous  supply  is  received  from  the  cerebro-spinal  system. 
Only  a  brief  discussion  of  the  eye,  ear,  and  nose  is  here  given. 

THE  EYE. 

There  are  three  coats  of  the  eye — an  external  fibrous  tunic,  a  mid- 
dle vascular  tunic,  and  an  inner  nervous  tunic. 

1.  The  external  coat  includes  the  cornea  and  sclerotic  mem- 
brane. 

The  cornea  is  composed  of  five  layers — (-1)  The  anterior  epithe- 
lium; (2)  the  anterior  limiting  membrane;  (3)  the  substance 
proper;  (4)  the  posterior  limiting  membrane;  (5)  the  posterior 
endothelium. 

The  sclerotic  membrane,  or  sclera,  resembles  the  substantia  pro- 
pria  of  the  cornea  and  consists  of  two  structures — (1)  bundles  of 
white  fibrous  tissue;  (2)  a  layer  of  loose  connective  tissue,  the  lam- 
ina supra  choroidea. 

2.  The  middle  tunic  comprises  the  choroid,  ciliary  body,  and  iris. 
The  choroid  consists  of  three  layers — (1)  the  choroidal  stroma, 

containing  blood-vessels;  (2)  the  capillary  networks;  (3)  the  vit- 
reous membrane. 

The  ciliary  body  comprises  three  portions — (1)  the  ciliary  ring; 
(2)  the  ciliary  processes;  (3)  the  ciliary  muscles. 

The  iris  comprises  the  following  structures :  (1)  The  anterior  en- 
dothelium; (2)  the  anterior  boundary  layer;  (3)  the  vascular  layer; 
(4)  the  posterior  boundary  layer;  (5)  the  pigment  layer. 

3.  The   nervous   tunic. — This  tunic  comprises  the  retina,  which 
consists  of  ten  layers — (1)  the  pigment  layer;  (2)  the  layer  of  rods 
and  cones;  (3)  the  external  limiting  membrane;  (4)  the  outer  nu- 
clear layer;  (5)  the  outer  reticular  layer;  (6)  the  inner  nuclear 
layer;  (7)  the  inner  reticular  layer;  (8)  the  ganglion-cell  layer; 
(9)  the  nerve  fibre  layer;  (10)  the  internal  limiting  membrane. 


142  NORMAL  HISTOLOGY. 

THE  EAR. 

The  specialized  nemo-epithelium  of  the  ear  is  found  in  the  in- 
ternal ear.  It  comprises  two  kinds  of  cells — the  sustentacular  cells 
and  the  hair  cells. 

THE  NOSE. 

The  neuro-epithelium  of  the  nose  consists  of  elongated  cells  with 
spherical  nuclei. 

Laboratory  exercise  No.  46. — The  eye.  Fix  in  chromic  acid,  harden 
in  alcohol,  and  stain  with  carmine,  method  No.  3.  Make  a  study  of  the 
structures  above  enumerated,  and  as  far  as  possible  demonstrate  the 
layers  of  each  coat.  What  is  the  character  of  the  crystalline  lens? 
The  vitreous  humor  is  the  same  in  character  as  the  jelly  of  Wharton — 
i.  e.,  mucous  tissue. 

MEMORANDA. 


PART   III. 


BACTERIOLOGY. 


Bacteriology  deals  with  minute  vegetable  organisms  known  as 
bacteria,  microbes,  germs,  etc.  The  science  is  comparatively  new, 
and  while  it  is  suggested  in  some  quarters  that  it  has  accomplished 
naught  of  practical  value  except  the  discovery  of  the  bacillus  of 
consumption,  thereby  emphasizing  the  importance  of  properly  dis- 
posing of  tubercular  sputum,  yet  this  alone  is  adequate  compensa- 
tion for  the  labor  thus  far  bestowed.  But  this  is  not  all.  The  work- 
ers in  this  field  have  discovered  the  specific  cause  of  a  number  of 
other  diseases,  the  means  of  preventing  the  spread  of  these  diseases, 
and  certain  remedies  of  inestimable  value — such  as  the  antitoxin  for 
diphtheria.  The  results  of  future  investigations  will  probably  ex- 
ceed the  hopes  of  the  most  sanguine. 

CHAPTER  XXII. 
CHARACTERISTICS  AND  CLASSIFICATION  OF  BACTERIA. 

Characteristics. — Bacteria  are  unicellular,  non-nucleated,  vegeta- 
ble organisms,  which  reproduce  by  normal  fission  and  by  endospores. 
With  but  three  exceptions,  they  are  devoid  of  chlorophyl.  They  are 
parasitic  and  saprophytic.  Many  infest  the  human  body,  some 
producing  infectious  diseases,  while  others  are  supposed  to  aid  in 
the  processes  of  digestion  and  assimilation.  They  assist  in  the  de- 
composition of  dead  organic  substances,  thus  performing  an  inesti- 
mable service  to  man.  They  reproduce  by  normal  fission  and  the 
formation  of  endospores.  Normal  fission  is  accomplished  by  the 
division  of  the  protoplasm  and  the  formation  of  a  partition  between 
the  two  halves.  As  the  cells  continue  to  multiply,  they  often  co- 
here, thus  forming  a  filament.  In  other  cases  the  cells  are  held 
together  in  masses,  called  zeoglcece.  An  endospore  is  formed  some- 

[143] 


144 


BACTERIOLOGY. 


times  in  the  middle  of  the  rod,  which  becomes  swollen  centrally, 
and  the  spindle-shaped  ceil  is  called  a  dostridium.  Often  the  spore 
occurs  in  the  end  of  the  cell;  again  the  whole  cell  may  assume  the 
function  of  a  spore,  giving  rise  to  the  so-called  arthrospore.  Spores 
are  designed  to  perpetuate  the  species  and  to  this  end  offer  great  re- 
sistance to  external  influences,  such  as  cold,  heat,  antiseptics,  etc. 
Dr.  Curtis  says :  "Bacillus  antliracis  retains  its  vitality  for  some 
time  in  absolute  alcohol  and  withstands  boiling  in  nutrient  solutions 
for  an  hour,  and  has  germinated  after  three  years7  confinement  in 
dry  air/' 

Classification   of   bacteria. — The  present  system  of  classification 
is  considered  imperfect.    The  outline  given  below,  while  not  com- 
plete, will  give  a  fair  idea  of  the  scheme,  of  classification  considered 
most  satisfactory  by  good  authorities : 
Classification: 

Kingdom — Vegetable. 

Series — Cryptogamia. 

Sub-kingdonx — Thallophyta. 
Class — Fungi. 

Sub-class — Schizomycetes. 


Sub-class. 


Group. 


Family. 


f  Coccaceae 

(spherical) 


Schizomycetes,  or 
Bacteria  . . 


Monomor- 
phous . . 


Genus. 

f  Micrococcus. 
Streptococcus. 
Diplococcus. 
Tetracoccus. 
Staphylococcus. 
Ascococcus. 
Sarcina. 


Pleomorphous 


f  Spirillum. 
I   Vibrio. 

iBaeteriaeea.J   %%$£*• 
(rod-shaped)  {   p^teus 

^  Bacterium. 

SpirulineaB <J   Spirulina. 

(  Leptothrix. 

Leptotrichese.  j   CrfiSthrix. 

[  Phragmidiothrix. 

Cladotricheae .  \   Cladothrix. 


BACTERIOLOGY.  145 


CHAPTER  XXIII. 

MORPHOLOGY,  KINDS,  AND  PRODUCTS. 
MORPHOLOGY. 

The  present  classification  of  bacteria  depends  largely  upon  their 
forms.  When  a  species  assumes  but  one  form,  it  is  said  to  be  mono- 
morphous;  but  if  it  possesses  several  forms,  it  is  pleomorphous. 

Monomorphous  bacteria  are  represented  by  three  important  di- 
visions :  Cocci,  spherical  cells ;  Bacilli,  or  rod-shaped  bacteria ;  and 
Spirilla,  or  curved  bacteria.  Cocci  are  represented  by  several  gen- 
era — Micrococcus,  in  which  the  cells  occur  singly;  Diplococcus,  in 
which  the  cells  occur  in  pairs,  the  result  of  binary  division;  Tetra- 
coccus,  in  which  the  cells  occur  as  tetrads;  Sarcina,  in  which  the 
cells  occur  in  cubes,  or  packets ;  Streptococcus,  where  Jhe  cells  occur 
in  chains,  or  filaments,  the  result  of  fission  in  one  direction ;  StapJiy- 
lococcus,  in  which  the  cells  occur  in  masses,  like  a  cluster  of  grapes : 
Ascococcus,  in  which  the  cocci  are  in  globular  masses. 

Spirilla  include  the  genera  Spirillum,  Vibrio,  and  Spirochoete. 
The  elements  are  curved,  sometimes  comma-shaped,  and  again  in 
long  spirals. 

Bacilli  are  represented  by  the  genera  Bacillus,  Proteus,  and  Bac- 
terium. The  species  of  these  genera  are  illustrated  by  rod-shaped 
cells.  The  rods  may  be  pointed  at  the  ends,  as  in  the  clostridium ; 
truncate,  as  with  anthracis;  round,  as  with  subtilis.  Some  form 
filaments,  as  anthracis;  others  are  always  single,  as  pyocyanus. 
Some  are  slender,  as  tuberculosis;  others,  large  and  thick,  as  sub- 
tilis. Involution  forms  occur  where  the  rod  deviates  from  the  char- 
acteristic form,  due  to  external  conditions  or  the  death  of  the  cell. 

Pleomorphus  bacteria  are  represented  by  Spirulina,  Leptothrix, 
and  Cladothrix.  Among  these  the  individuals  of  each  species  as- 
sume more  than  one  form. 

KINDS  OF  BACTERIA. 

The  following  are  the  important  kinds  of  bacteria : 

1.  Parasitic,  those  depending  for  subsistence  upon  a  living  host. 
10 


146  BACTERIOLOGY. 

2.  Saprophytic,  those  subsisting  upon  dead  organic  matter. 

3.  Aerobic,    those  requiring  oxygen. 

4.  Anaerobic,  those  subsisting  without  oxygen. 

5.  Facultative,    those    that    are    anaerobic,    but    may    become 
aerobic;  and  those  saprophytic  that  may  become  parasitic. 

6.  Pathogenic,  those  producing  diseases  in  man  and  animals. 

7.  Chromogenic,    those  producing  pigments. 

8.  Zymogenic,  those  producing  fermentations. 

9.  Motile,  those  having  independent  motion. 

10.  Liquefying,    those  that  produce  a  ferment  which  liquefies 
solid  nutrient  gelatin. 

PRODUCTS. 

Bacteria  are  powerful  agents  in  breaking  up  complex  chemical 
substances  into  simple  ones.  They  attack  the  tissues  of  living 
organisms  and  produce  the  toxins  and  ptomaines  which  cause  the 
symptoms  of  destructive  diseases.  They  assist  animals  in  destroy- 
ing dead  organic  matter,  else  the  earth  would  be  covered  with 
its  dead.  Thus,  by  their  cooperation  with  other  humble  or- 
ganisms, they  make  life  upon  the  earth  possible.  They  assist  in 
manufacturing  articles  of  economic  value,  such  as  butter,  cheese, 
etc.  They  convert  starch  into  sugar,  dissolve  cellulose,  change  al- 
bumin from  an  insoluble  to  a  soluble  form,  convert  urea  into  am- 
monium carbonate,  produce  lactic  acid  in  milk,  produce  acetic  acid 
from  alcohol,  and  manufacture  bright  pigments. 

The  pigment  formed  by  Badllis  prodigiosus  was  once  supposed 
by  the  superstitious  to  be  blood  formed  by  supernatuTal  power.  Cer- 
tain gaseous  products  are  sometimes  evolved  by  the  action  of  bac- 
teria. The  foul  odors  from  putrefying  bodies  may  be  ascribed  to 
their  action.  Among  the  common  gases  which  are  liberated  from  or- 
ganic substances  by  the  agency  of  bacteria  may  be  named  nitrogen, 
carbon  di-oxide,  and  sulphuretted  hydrogen.  The  demonstration  of 
gaseous  products  may  be  made  by  the  growth  of  certain  species  in 
nutrient  media  in  a  saccharometer.  Indol  is  produced  by  some  spe- 
cies. The  test  for  this  substance  is  made  by  adding  to  the  peptone 
solution  in  which  the  bacteria  have  been  vegetating  for  twenty-four 
hours  about  ten  drops  of  c.  p.  sulphuric  acid.  The  development  of  a 


MORPHOLOGY,  KINDS,  AND  PRODUCTS.  147 

rose-color  indicates  the  presence  of  indol  and  nitrites.  Should  no 
rose-color  appear,  another  tube  should  be  tested,  adding,  first,  1  c.  c. 
of  .01  per  cent  solution  of  sodium  nitrite,  and  then  the  sulphuric 
acid.  The  formation  of  a  rose-color  indicates  the  presence  of  indol 
alone. 

Laboratory  exercise  No.  47. — Morphology.  Make  cover-glass  prepara- 
tions of  species  of  cocci,  bacilli,  and  spirilla.  Note  the  peculiar  form 
of  the  individuals  of  each  species.  To  demonstrate  the  different  kinds 
of  cocci,  the  following  species  may  be  used:  Micrococcus  urese,  Diplo- 
coccus  pneumonias,  Sarcina  lutea,  Streptococcus  pyogenes,  Staphylococ- 
cus  pyogenes  aureus,  and  Ascococcus  Billrothii. 

Apply  to  the  surface  of  a  cover-glass  some  of  the  scrapings  obtained 
from  the  teeth  just  under  the  gums.  Cover  this  with  another  glass  and 
by  pressure  spread  out  the  material  so  as  to  make  a  thin  film.  Dry,  fix, 
and  stain.  (See  method  No.  10.)  Examine  your  preparation  and  ob- 
serve cocci,  spirilla,  and  bacilli.  Note  the  large  ribbon-like  forms, 
which  probably  represent  LeptotJirix  buccalis.  Make  drawings  to  illus- 
trate a]l  of  these  forms. 

Laboratory  exercise  No.  48. — Motility.  Apply  to  a  clean  slide  some 
of  the  scum  upon  the  surface  of  hay  infusion.  Cover  and  note  the  slen- 
der filaments  made  up  of  rod-like  cells.  Each  cell  represents  an  indi- 
vidual of  Bacillus  subtilis.  Observe  the  slow,  gliding  motion  of  the  fila- 
ments. How  is  this  motion  secured?  Look  for  other  bacteria.  Some 
may  be  found  with  a  vibratory  motion.  If  this  motion  is  confined  to 
one  place  without  producing  any  progress  across  the  field  of  vision,  it 
is  purely  physical,  the  so-called  Brownian  movement. 

Laboratory  exercise  No.  49. — Products.  Fill  the  long  arm  of  the  Sac- 
charometer  with  bouillon  and  inoculate  the  medium  with  some  zymogenic 
species.  The  formation  of  gases  in  the  upper  end  of  the  arm  indicates 
the  action  of  the  bacteria.  Make  the  test  for  indol,  as  described  above, 
using  as  a  culture-medium  Dunham's  Peptone  solution,  which  is  pre- 
pared by  boiling,  filtering,  and  sterilizing  a  mixture  of  10  grams  of  pep- 
tone, 5  grams  of  sodium  chloride,  and  1  liter  of  water. 


FORMS  OF  BACTERIA. 


A.  Cocci.  B.  Bacilli. 


A.  Cocci:   (a)  Micrococcus;  (b)  Diplococcus;  (c)  Tetracoccus;  (d)  Sarcina;  (e)  Streptococcus; 
(f)  Staphylococcus;  (g)  Ascococcus;  (h)  Zob'gloea. 

B.  Bacilli:    (a)  Single  cells;  (b)  Filaments;  (c)  Cells  with  round,  pointed,  and  truncate  ex- 
tremities; (d)  Polar  spore;  (e)  Glostridium  with  central  spore. 

C.  Spirilla.  D.  Pleomorphous  Forms. 


C.  Spirilla:   (a)  Spiral  filament;  (b)  Comma-shaped  cells. 

D.  Pleomorphous  forms:  (a)  Spirulina;  (b)  Leptothrix;  (c)  Cladothrix. 

[148] 


BACTERIOLOGY.  149 


CHAPTER  XXIV. 

SIZE,  NUMBERS,  AND  DISTRIBUTION. 

Size  and  numbers. — The  unit  of  measurement  for  bacteria  is 
the  micromillimeter,  which  is  the  thousandth  part  of  a  millimeter. 
It  is  represented  by  the  Greek  letter  /*.  The  size  of  Bacillus  tuber- 
culosis is:  Length,  1.5/ji  to  4,u;  diameter,  0.2,u  to  0.5, a.  Some 
cocci  are  as  small  as  0.1 5 /A  in  diameter;  others  as  large  as  2.8^i 
in  diameter.  Bacilli  range  from  lxO.2//  to  5xl.5,u.  Some  spirilla 
are40/jt  long.  The  number  of  known  species  is  upward  of  1,000 
The  individuals  of  any  species  are  countless.  Dr.  Sternberg  states 
that  a  milligram  of  the  pure  culture  of  StapJiylococcus  pyogenes 
aureus  contains  8,000,000,000  individuals.  The  weight  of  an  av- 
erage bacterium  has  been  estimated  by  Nageli  to  be  1-10,000,000,000 
milligram. 

The  following  estimates,  as  given  by  Williams,  will  give  some 
conception  as  to  the  number  of  bacteria  that  form  a  part  of  the  in- 
visible world  of  teeming  organisms.  The  number  of  individuals  in 
1  c.  c.  of  virgin  soil  is  estimated  to  be  upward  of  100,000.  Ordinary 
milk  contains  more  than  20,000  to  1  c.  c.  The  number  of  bacteria 
in  a  milligram  of  human  fecal  matter  will  range  from  70,000  to 
33,000,000. 

Distribution. — The  estimates  just  given  will  suggest  that  bacteria 
are  very  widely  distributed.  Their  spores  float  upon  the  dust  of  the 
atmosphere  in  untold  millions ;  they  swarm  in  the  water  we  drink : 
they  teem  in  the  soil  to  the  depth  of  three  feet ;  they  abound  in  food 
and  in  all  decaying  substances;  and  they  take  up  their  abode  in 
the  human  body,  being  present  in  the  alimentary  tract  in  large 
numbers,  except  in  new-born  infants.  It  is  believed  that  the  air 
upon  the  high  seas  and  upon  mountain  tops,  the  deeper  layers  of  the 
soil,  the  water  of  uncontaminated  springs,  and  tfye  tissues  and  fluids 
of  the  normal  body  which  are  not  exposed  to  the  external  atmos- 
phere are  free  from  their  presence. 

The  presence  of  bacteria  in  soil,  air,  water,  milk,  blood,  urine, 
and  fecal  matter  may  be  demonstrated  by  making  plate  cultures 


150  BACTERIOLOGY 

from  the  substances  to  be  tested.  If  properly  prepared  the  plate 
will  exhibit  as  many  colonies,  approximately,  as  there  were  indi- 
viduals in  the  known  amount  of  the  material  used.  This  furnishes 
a  working  basis  for  counting  the  number  of  specimens  in  a  given 
quantity  of  any  substance.  By  exposing  a  sterilized  Petri  dish  con- 
taining agar  media  to  the  air  for  a  few  moments  and  then  cover- 
ing, in  a  day  or  so  many  colonies  will  appear,  indicating  the  kinds 
and  number  of  species  which  occur  in  the  atmosphere.  By  plating, 
these  can  be  isolated,  studied,  and  classified. 

While  in  normal  condition  the  human  body  is  comparatively 
free  from  bacteria,  yet  the  alimentary  and  respiratory  tracts  always 
contain  large  numbers,  and,  under  abnormal  conditions,  the  tissues, 
blood,  lymph,  and  urine  often  become  infested.  The  products  of 
the  mucous  membrane  (especially  the  hydrochloric  acid)  and  the 
serum  of  the  blood,  which  are  germicidal,  as  well  as  the  phagocytes, 
are  generally  effectual  checks  to  the  invading  hosts. 

The  outer  layers  of  the  skin  furnish  the  abode  of  many  species, 
and  it  is  claimed  to  be  impossible  to  dislodge  all  the  germs  that 
occur  under  the  nails. 

There  are  certain  agencies  which  influence  the  growth  and  dis- 
tribution of  bacteria.  Electricity  arrests  growth.  Sunlight  will 
kill  Bacillus  tuberculosis  and  other  species,  a  few  hours  of  sunlight 
being  sufficient  to  kill  the  vegetative  cells  of  Bacillus  anthracis. 
Acids  and  oils  are  usually  antiseptic.  Some  species  require  oxygen, 
while  others  will  not  grow  in  its  presence.  Many  species  can  with- 
stand severe  cold>  but  quickly  succumb  to  a  high  temperature.  The 
temperature  at  which  a  species  dies  is  called  its  thermal  death 
point.  The  thermal  death  point  of  a  considerable  number  of  spe- 
cies is  about  60  degrees  Centigrade.  There  is  a  certain  temperature 
most  favorable  to  the  growth  of  each  species.  This  for  many  spe- 
cies is  about  35  degrees  Centigrade. 

Laboratory  exercise  No.  5Q.^-Bacteria  in  air,  water,  soil,  etc.  Expose 
to  the  air  the  agar-agar  in  a  sterilized  Petri  dish  for  a  few  moments. 
Examine  in  a  day  or  so  and  observe  and  count  the  colonies  upon  the 
surface  of  the  medium.  Note  that  they  differ  in  form  and  color.  In- 
oculate five  test-tubes  of  agur-ag-ar,  one  with  each  of  the  following  sub- 
stances: Soil,  ordinary  drinking*  water,  milk,  urine,  and  saliva.  These 
materials  should  be  collected  in  sterilized  containers.  Label  each  tube, 
and  in  a  few  days  examine  for  any  growths  which  may  have  appeared. 


BACTERIOLOGY.  151 


CHAPTER  XXV. 

CULTIVATION  AND  SYSTEMATIC  STUDY  OF  BACTERIA. 
CULTIVATION  OF  BACTERIA. 

This  is  accomplished  by  the  use  of  certain  media  upon  which  the 
species  to  be  cultivated  will  grow.  Such  are  potato,  blood  serum, 
gelatin,  and  agar-agar.  The  medium,  when  prepared,  is  placed  in 
cotton-stoppered  tubes  and  then  sterilized.  In  the  case  of  gelatin 
and  agar-agar,  a  steam  sterilizer  can  be  used,  and  sterilization 
should  be  made  on  three  successive  days,  from  fifteen  minutes  to 
one  hour  each  day. 

CULTURE  MEDIA. 

The  following  formulas  for  the  preparation  of  culture  media  will 
be  useful: 

1.  Meat  broth. — To  one  liter  of  water  add  one  pound  of  finely- 
chopped  lean  meat,,  free  from  all  fat.    Let  stand  over  night,  or  heat 
for  one  hour,  but  do  not  boil.    Filter. 

2.  Bouillon.  — To  one  liter  of  meat  broth  add  ten  grams  of  pep- 
tone and  five  grams  of  sodium  chloride.     The  peptone  and  sodium 
chloride  should  be  thoroughly  mixed  in  a  mortar  with  water,  until 
a  thin  paste  is  formed,  before  adding  them  to  the  meat  broth.    Cook 
one  hour,  filter,  and  alkalize  with  a  solution  of  sodium  carbonate. 
Sterilize. 

3.  Agar-agar.  — To  one  liter  of  bouillon  add  fifteen  grams  of  agar. 
Cook  in  sterilizer,  or  double  sauce-pan,  until  agar  is  dissolved,  one 
to  three  hours.     Neutralize  with  solution  of  c.  p.  Na2  Co3.     Filter. 
Cool  to  body  temperature  and  add  the  whites  of  two  eggs,  which 
have  been  previously  mixed  with  100  c.  c.  of  water.    Cook  one  hour. 
Filter  with  coarse  'filter  to  remove  coagulated  albumen.    Heat  again 
and  filter  with  best  filter  paper  previously  moistened  with  boiling 
water.     Should  any  of  the  medium  fail  to  filter  through  the  first 
paper,  it  should  be  heated  again,  and  a  second  paper  used  for  that 
portion.     Fill  tubes  and  sterilize  on  three  successive  days.     Cool 
with  tubes  in  oblique  position. 


152  BACTERIOLOGY. 

4.  Nutrient  gelatin.— To  one  liter  of  bouillon  add  100  grams  of 
finest  gelatin.     Heat  twenty  minutes  in  steam  sterilizer.     Alkalize 
with  solution  of  c.  p.  sodium  carbonate  and  filter  with  filter  paper 
in  steam  sterilizer.    Fill  tubes.    Sterilize  for  three  successive  days, 
fifteen  minutes  each  day. 

5.  Blood    serum. — Collect  blood  in  a  sterilized  container.    When 
coagulated,  loosen  clot  and  let  stand  twenty-four  hours  in  a  cool 
place.    Remove  clear  serum  and  fill  sterile  test-tubes  with  the  same. 
Coagulate  at  65  degrees  to  75  degrees  Centigrade.     Sterilize  at  58 
degrees  Centigrade,  one  hour  each  day  for  six  days. 

6.  Potato   medium. — After  thoroughly  washing  potatoes  in  soap 
and  water  and  removing  eyes  and  spots,  immerse  in  mercuric  chlo- 
ride solution,  1  to  1,000,  for  ten  minutes.     Make  cylinders  of  the 
potatoes  the  size  of  tubes;  bisect  obliquely,  placing  each  half  in  a 
tube.    Sterilize  for  three  successive  days,  a  half  hour  each  day. 

As  already  suggested,  each  medium,  when  prepared,  is  to  be 
placed  in  cotton-plugged  tubes,  and  then  sterilized.  The  cotton 
proves  a  perfect  filter  for  the  bacteria.  Agar-agar  may  be  kept  for 
months  without  any  indication  of  growth  of  any  kind,  the  cotton 
plug  preventing  all  access  of  germs  from  the  outside. 

INOCULATION. 

The  inoculation  of  the  media  is  accomplished  by  means  of  a  ster- 
ilized platinum  wire.  A  small  portion  of  the  pure  culture  of  the 
species  desired  is  caught  upon  the  loop  at  the  end  of  the  wire  and 
then  drawn  over  the  surface  of  the  medium.  Care  should  be  taken 
to  sterilize  the  wire  both  before  and  after  using. 

PLATING. 

A  pure  culture  of  a  species  is  obtained  by  plating.  This  is  ac- 
complished by  gently  heating,  until  melted,  the  nutrient  gelatin,  or 
agar-agar,  in  three  tubes.  With  a  sterilized  platinum  wire,  a  small 
portion  of  the  substance  containing  the  bacteria  is  transferred  to 
the  liquefied  gelatin,  or  agar-agar,  in  tube  number  one.  Then,  after 
sterilizing  the  wire  again,  a  small  quantity  of  the  contents  of  tube 
one  is  transferred  to  tube  two.  In  like  manner,  tube  three  is  inocu- 
lated from  tube  two.  Then  the  contents  of  the  tubes  are  trans- 


CULTIVATION  AND  SYSTEMATIC  STUDY  OF  BACTERIA.     153 

ferred  to  three  sterilized  Petri  dishes.  After  numbering  and  label- 
ing, the  dishes  are  set  aside  for  future  examination.  If  colonies  oc- 
cur on  plates  two  and  three,  they  are  probably  pure  cultures  of  the 
species  desired.  From  these  colonies  tubes  containing  media  can 
be  inoculated. 

HANGING-DROP  CULTURES. 

It  is  often  very  desirable  to  make  a  microscopic  study  of  bacteria 
and  other  organisms  in  the  process  of  growth.  This  is  accom- 
plished by  resorting  to  the  hanging  drop  culture.  A  small  drop  of 
the  liquid  media  containing  the  species  to  be  studied  is  transferred 
by  a  platinum  loop  to  the  center  of  a  sterilized  cover-glass.  This  is 
then  inverted  upon  a  slide  in  the  center  of  which  a  concavity  has 
been  ground  out.  The  edges  of  the  cover-glass  are  then  sealed  with 
a  layer  of  vaseline  applied  with  a  camelVhair  brush.  Th<3  prepara- 
tion may  then  be  studied  from  time  to  time,  the  focusing  being  ap- 
plied to  the  edges  of  the  preparation,  rather  than  the  center,  which 
will  generally  be  found  opaque. 

INOCULATION  OF  ANIMALS. 

To  save  human  life  it  is  of  1  en  quite  necessary  to  sacrifice  the  lives 
of  lower  animals.  The  experiments  of  bacteriologists,  while  ap- 
pearing to  the  superficial  observer  as  almost  merciless,  are  in  the 
interests  of  the  highest  humanity  and  are  destined  not  only  to  di- 
minish in  a  large  degree  the  sum  of  human  suffering,  but  to  bring 
alleviation  to  lower  animals,  at  whose  expense  the  requisite  knowl- 
edge is  sought.  The  life  of  man  outweighs  that  of  a  mouse  or 
"  many  sparrows.*'  For  purposes  of  experimentation,  such  animals 
as  mice,  rats,  guinea  pigs,  and  rabbits  are  generally  employed.  In- 
oculations are  made  in  the  ear,  at  the  root  of  the  tail,  and  elsewhere. 
The  hair  is  first  removed  by  cutting  or  searing.  A  V-shaped  inci- 
sion is  then  made,  and  the  infected  material  inserted  by  means  of  a 
platinum  wire.  Inoculation  of  the  blood  may  be  made  with  a  bac- 
teriological syringe. 

SYSTEMATIC  STUDY  OF  BACTERIA. 

The  identification  of  any  species  can  only  be  made  after  a  thor- 
ough study  of  its  characteristics.  Even  then  the  determination  will 


154  BACTERIOLOGY 

sometimes  be  attended  with  considerable  difficulty  and  doubt.  In 
the  systematic  study  of  an  unknown  species,  the  following  outline 
may  prove  of  service:  (1)  Name,  (2)  habitat,  (3)  growth  on  me- 
dia, (4)  temperature,  including  that  of  most  favorable  growth  and 
the  thermal  death  point,  (5)  relation  of  growth  to  oxygen,  (6) 
gas  formation,  (7)  chemical  reaction,  (8)  formation  of  indol,  (9) 
pigmentation,  (10)  pathogenesis,  (11)  aniline  reaction,  (12)  mo- 
tility.  (13)  morphology,  (14)  size,  (15)  spore  formation. 

When  these  tests  have  been  made,  the  classification  may  be  de- 
termined by  using  analytic  keys,  such  as  are  found  in  the  valuable 
works  of  Sternberg  and  Crookshank. 

Laboratory  exercise  No.  51. — Culture  Media.  Let  the  student  prepare 
or  assist  the  instructor  in  preparing1  the  following  media:  Bouillon, 
agar-agar,  blood  serum,  nutrient  gelatin,  and  potato  medium.  Make 
inoculations  upon  agar-agar  as  directed  above.  The  tubes  should  be 
held  in  the  left  hand,  between  the  thumb  and  forefinger,  in  such  a  way 
that  the  palm  of  the  hand  will  be  vertical  and  the  tubes  but  slightly 
inclined.  The  cotton  plugs,  when  removed,  may  be  held  between  the 
fingers.  The  greatest  care  should  be  exercised,  always  sterilizing  the 
platinum  needle  before  and  after  using.  .Make  a  stab-culture  of  some 
anaerobic  species.  This  is  accomplished  by  holding  the  tube  in  a  ver- 
tical position,  using  a  platinum  wire  with  small  loop,  and  plunging  this 
through  the  center  of  the  medium  from  the  surface  to  the  bottom  of  the 
tube. 

Experiments  with  animals.  Clip  the  hair  from  the  base  of  the  tail  of 
a  mouse.  Make  a  V-shaped  incision  and  insert  into  the  wound  some  of 
the  saliva  of  the  mouth.  Saliva  often  contains  Diplococcus  pneumoniae, 
which  will  cause  the  death  of  an  inoculated  mouse  in  a  few  hours. 
Other  inoculations  may  be  made  as  desired. 

Laboratory  exercise  No.  52. — Hanging-drop  Cultures.  Prepire  a  hang- 
ing-drop culture  upon  which  have  been  sown  some  spores  of  any  species 
of  mold,  such  as  Penicillium  glaucum.  After  a  few  days  examine.  The 
spores  of  molds  may  sometimes  be  mistaken  for  cocci.  The  hyphae, 
or  slender  filaments,  which  compose  their  structure,  may,  when  broken 
into  fragments,  have  some  resemblance  to  the  cells  of  bacilli.  The 
hyphae  develop  from  the  spores,  producing  three  characteristic  por- 
tions— the  root  hyphas;  the  mycelium,  or  prostrate  portion;  and  the 
aerial  hyphae,  upon  the  extremities  of  which  the  sporangia  containing 
the  spores  are  developed.  Also  make  hanging  drop  cultures  of  species 
of  bacteria,  and  study  the  same  from  time  to  time. 

Laboratory  exercise  No.  53. — A  systematic  study  of  Bacteria.  Make  a 
systematic  study  of  Bacillus  prodigiosus  and  other  common  species  ac- 
cording to  the  method  suggested  above.  Fill  out  the  outline  on  page  155 
and  make  drawings  of  agar  cultures  and  the  microscopic  elements. 


OUTLINE  FOR  SYSTEMATIC  STUDY. 


Species  , 

1.  Habitat 

2.  Growth  on  media — 

(1)  Gelatin  

(2)  Agar-agar 

(3)  Blood-serum 

(4)  Potato 

3.  Relation  to  temperature — 

(1)  Best  growth 

(2)  Thermal  death-point 

4.  Relation  to  oxygen 

5.  Gas  formation 

6.  Chemical  reaction 

7.  Formation  of  indol 4 

8.  Pigmentation 

9.  Pathogenesis 

10.  Anilin  reaction  (Gram's  method) . 

11.  Motility   

12.  Morphology 

13.  Size 

14.  Spore  formation 

15.  Classification . . 


[155] 


156  BACTERIOLOGY. 


CHAPTER  XXVI. 

MICROSCOPIC  TECHNIQUE. 

I.  REAGENTS  AND  STAINS. 

(1)  DECOLORIZING  SOLUTIONS. 

Twenty-five  per  cent  aqueous  solutions  of  hydrochloric,  nitric, 
and  sulphuric  acids  may  be  used  for  decolorizing. 

(2)  ACID  ALCOHOL. 

Hydrochloric  acid 1  part 

Alcohol  (seventy  per  cent) 100  parts 

(3)  IODINE  SOLUTION. 

Iodine 1  gram 

Potassium  iodide 2  grams 

Water 300  cc. 

(4)  CARBOL  FUCHSIN. 

Fuchsin 1  cc. 

Alcohol 10  cc. 

Dissolve  and  add  10  c.  c.  of  five  per  cent  solution  of  carbolic  acid. 
Filter. 

(5)  ACID  METHYLENE  BLUE. 

Sulphuric  acid 16  cc. 

Water 90  cc. 

Methylene  blue 2  grams 

This  stain  should  be  prepared  fresh  from  time  to  time.     The 
carbol  fuchsin  improves  with  age. 

(6)  LOFFLER'S  ALKALINE  METHYLENE  BLUE. 

Concentrated  alcoholic  solution  of  methy- 

lene  blue 30  c. 

Potassum  hydrate  (Aq.  Sol.,  1-10,000) 100  cc. 

This  is  especially  useful  in  staining  the  baccillus  of  diphtheria. 

(7)  ANILINE-WATER  GENTIAN-VIOLET. 

Aniline  oil 5  cc. 

Water..  ..100  cc. 


MICROSCOPIC  TECHNIQUE.  157 

Mix,  shake  vigorously,  filter;  the  fluid  after  filtration  should  be 
perfectly  clear;  add 

Alcohol 10  cc. 

Alcoholic  solution  of  gentian-violet 11  cc. 

This  solution  should  be  freshly  prepared  about  every  two  weeks. 

(8)  LOFFLER'S  MORDANT  FOR  FLAGELLA. 

Tannic  acid 2  grams 

Water 8  cc. 

Saturated  solution  of  ferrous  sulphate 5  cc. 

Saturated  alcoholic  solution  of  fuchsin 1  cc. 

(9)  ANILINE-WATER  DYE   FOR  STAINING  SPORES. 

Saturated  alcoholic  solution  of  fuchsin  or 

gentian-violet <• 11  parts 

Aniline  oil  water 100  parts 

Abs.  alcohol 10  parts 

Keeps  well  for  ten  days. 

(10)  AQUEOUS  STAINS. 

Saturated  aqueous  solutions  of  fuchsin,  gentian- violet,  and 
methyline  blue  will  be  found  useful  for  all  simple  staining. 

(11)  ALCOHOLIC  SOLUTIONS. 

Saturated  alcoholic  solutions  of  fuchsin,  gentian-violet,  and 
methyline  blue  should  be  kept  on  hand  to  be  used  in  simple  staining 
and  in  connection  with  other  stains. 

II.  STAINING  METHODS, 

(1)  SIMPLE  STAINING. 

This  consists  in  using  a  single  stain.  The  process  is  given  on 
page  27,  method  No.  10. 

(2)  DOUBLE  STAINING. 

This  consists  in  using  two  stains,  one  to  stain  spores,  protoplasm, 
etc.,  and  the  other  as  a  ground  stain.  The  following  methods  will 
illustrate  double  staining: 


158  BACTERIOLOGY. 

Method  No.  XII. — Staining  of  Spores. 

(a)  Make  a  cover-glass  spread,  dry  and  pass  three  times  through  the 
flame. 

(b)  Add  aniline-water  gentian-violet. 

(c)  Heat  until  the  preparation  begins  to  boil;  remove  for  a  minute. 
Repeat  this  process  six  times. 

(d)  Wash  in  three  per  cent  hydrochloric  acid-alcohol  one  minute 

(e)  Wash  in  water. 

(f)  Counter-stain  with  aqueous  methylene  blue  half  a  minute. 

(g)  Wash  in  water. 

(h)  Dry  and  clear  up  with  xylol. 
(i)    Mount  in  balsam. 

Method  No.  XIII.— Staining  of  Flagella. 

(a)  Mix  upon  the  cover-glass  a  portion  of  the  culture  with  a  drop  of 
water,  using  care  not  to  break  off  the  delicate  flagella. 

(b)  Dry  and  pass  three  times  through  a  flame. 

(c)  Apply  Loffler's  mordant  one  minute,  warming  gently. 

(d)  Wash  in  water. 

(e)  Stain  with  aniline-water  fuchsin. 

(f)  Wash  in  water. 

(g)  Dry  and  mount  in  balsam. 

Method  No.  XIV.— Grain's  Method  for  Bacteria. 

(a)  Make  a  cover-glass  preparation  by  the  usual  method. 

(b)  Stain  with  aniline-water  gentian-violet  solution,  two  to  five  min- 
utes, warming  slightly. 

(c)  Add  Gram's  iodine  solution  one  and  one-half  minutes. 

(d)  Apply  alcohol,  repeatedly,  as  long  as  stain  continues  to  come 
away  from  the  preparation. 

(e)  Wash  in  water  and  examine  as  a  water-mount. 

(f )  If  desired,  dry  and  mount  in  balsam. 

Method  No.  XV. — Gabbet's  Method  for  Tuberculosis,  etc. 

(a)  Make  a  cover-glass  smear  of  the  sputum,  pus,  blood,  or  urine  to 
be  examined.     After  the  preparation  is  dry,  affix  by  passing  three  times 
through  the  flame. 

(b)  Using  a  Cornet  forceps,  apply  carbol-fuchsin  five  to  ten  minutes, 
heating  until  steam  appears. 

(c)  Wash  in  water. 

(d)  Apply  alkaline  methylene  blue  for  one  minute. 

(e)  Wash  in  water. 

(f)  Dry  and  mount  in  balsam. 


MICROSCOPIC  TECHNIQUE.  159 

Staining  Tissues  for  Bacteria. 

Tissues  may  be  stained  by  Gram's  method  or  by  the  following 
process : 

Method  No,  XVI. — Method  for  Staining  Bacteria  in  Sections, 

(a)  Using  an  aqueous  solution  of  fuchsin,  gentian-violet  or  methy- 
lene  blue,  apply  stain  for  about  five  minutes. 

(b)  Wash  in  water. 

(c)  Apply  an  aqueous  solution  of  acetic  acid,  one  per  cent,  for  one 
minute. 

(d)  Apply  alcohol  one  to  two  minutes. 

(e)  Clear  up  with  xylol. 

(f )  Mount  with  balsam. 

MEMORANDA. 


160  BACTERIOLOGY. 

CHAPTER  XXVII. 
NON-PATHOGENIC  BACTERIA. 

Material  for  the  practical  study  of  non-pathogenic  species  may 
be  obtained  from  air,  water,  soil,  and  other  sources.  The  biological 
characteristics  of  a  few  of  the  more  common  species  are  here  given 
to  assist  the  student  in  experimental  work. 

I.  Bacillus  Prodigiosus. 

This  species  is  a  chromogcnic,  non-motile,  facultative  anaerobic 
saprophyte.  It  produces  a  pigment-forming  body,  which  becomes 
red  by  the  action  of  oxygen.  The  pigment  gives  rise  to  the  "  red 
mould  "  of  bread.  The  rods  are  short,  often  in  filaments,  without 
spores.  It  grows  rapidly  upon  agar-agar,  or  potato,  at  the  room 
temperature,  and  soon  liquefies  nutrient  gelatin.  It  grows  best  at 
25  degrees  Centigrade.  It  may  be  obtained  from  the  air. 

II.  Bacillus  Acidi  Lactici. 

Bacillus  acidi  lactici  occurs  in  sour  milk,  producing  lactic  acid. 
It  is  a  non-motile,  facultative  anaerobic  saprophyte.  It  produces  a 
whitish  growth  on  agar-agar,  does  not  liquefy  gelatin,  ancl  the  rods 
occur  in  pairs  or  short  filaments,  producing  large  shining  polar- 
spores.  It  causes  milk  to  sour,  changing  its  sugar  into  lactic  acid 
and  CO  2,  and  precipitates  casein.  It  will  grow  at  10  degrees  Cen- 
tigrade; but,  when  cultivated  for  several  generations,  it  loses  its 
power  to  produce  fermentation.. 

III.  Bacillis  Subtilis. 

This  species  may  be  obtained  from  hay  infusions,  air,  water,  soil, 
etc.  It  produces  a  grayish  growth  on  agar,  and  liquefies  gelatin.  It 
is  a  motile  aerobic  saprophyte,  and  grows  rapidly  at  ordinary  tem- 
peratures. The  rods  are  thick  and  stout,  with  rounded  extrem- 
ities, and  provided  with  flagella.  It  produces  motile  spores. 

IV.  Bacillus  Violaceus. 

This  bacillus  is  found  in  water.  It  is  aerobic,  motile,  and  chromo- 
genic;  grows  at  room  temperature,  and  on  agar  produces  a  violet- 


NON-PATHOGENIC  BACTERIA.  161 

colored  covering  which  lasts  for  years.  The  rods  are  slender,  with 
rounded  ends,  and  produce  small  oval  spores.  It  grows  upon  agar 
and  liquefies  gelatin. 

V.  Proteus  Vulgaris. 

Proteus  vulgaris  is  found  in  putrefying  animal  matter;  is  a  facul- 
tative anaerobic  motile  saprophyte;  has  rods  with  rounded  ends, 
which  grew  into  flexible  filaments;  produces  a  whitish  growth  on 
agar,  and  liquefies  gelatin;  forms  H2  S,  and  causes  putrefaction,  oc- 
casionally being  pathogenic  to  man. 

VI.  Micrococcus  Urese. 

This  species  may  be  obtained  from  cystitic  and  decomposing  urine. 
The  cocci  occur  singly,  in  pairs,  or  in  filaments.  It  is  an  aerobic 
saprophyte,  grows  readily  at  room  temperature,  and  does  not  liquefy 
gelatin.  Plate  cultures  appear  like  a  drop  of  wax  upon  the  sur- 
face. 

VII.  Sarcina  Lutea. 

Sarcina  lutea  may  be  obtained  from  the  air.  It  is  an  aerobic 
chromogenic  species,  whose  cocci  occur  in  'pairs,  tetrads,  and  pack- 
ets. The  pigment  is  yellow.  It  liquefies  gelatin  slowly. 

VIII.  Spirillum  Rubrum. 

This  is  a  motile  chromogenic  facultative  anaerobic  species.  It 
may  be  found  in  the  putrefying  cadaver  of  a  mouse.  The  spirals 
make  three-quarter  turns.  It  groAvs  on  agar,  stab  cultures,  form- 
ing a  red  pigment. 

Laboratory  exercise  No.  54. — Bacillus  subtilis.  Prepare  a  pure  cul- 
ture of  this  species  and  inoculate  tubes  of  agar  and  gelatin.  Make  a 
study  of  the  growths  upon  these  media,  describing-  each.  Make  a  water- 
mount  and  demonstrate  the  motility  of  the  rods  and  filaments.  Make  a 
cover-glass  preparation  and  stain  with  gentian-violet,  method  No.  10. 
Demonstrate  flagella,  staining  by  method  No.  13.  Demonstrate  spores 
by  method  No.  12.  Prepare  an  outline  of  this  species  as  indicated  on 
page  155.  Make  drawings  of  cultures  and  rods. 

Laboratory  exercise  No.  55. — Micrococcus  ureae.    Obtain  plate  cultures 
from  decomposing  urine.     Note  the  wax-like  colonies.     Make  a  cover- 
glass  preparation  and  stain  with  gentian-violet.     Observe  the  spherical 
cells  arranged  singly,  in  pairs,  and  in  chains.     How  does  this  species 
11 


162  BACTERIOLOGY. 

affect  urea?     Prepare  an  outline,  as  with  the  last  species,  and  make 
drawings  of  cultures  and  cells. 

Laboratory  exercise  No.  5Q.—8arcina  luted.  Expose  agar-agar  in  a 
Petri  dish  to  the  air,  and  from  the  j^ellowish  colonies  which  develop 
prepare  plates.  Inoculate  tubes  (from  the  pure  cultures  thus  obtained) 
of  agar  and  gelatin.  Describe  the  growth  in  each  tube.  Stain  by 
method  No.  10.  Note  the  cocci,  arranged  singly,  in  pairs,  in  tetrads, 
and  in  packets.  Make  drawings  of  cultures  and  cells. 

Laboratory  exercise  No.  57.  — Spirillum  rubrum.  Obtain  a  pure  culture 
of  this  species.  Prepare  a  cover-glass  spread,  and  stain  with  gentian- 
violet,  method  No.  10.  Note  the  spirals  and  count  the  turns  in  each. 
Drawings. 

Note. — Other  species  may  be  substituted  for  those  given  above,  and 
additional  ones  may  be  required. 

MEMORANDA. 


NON-PATHOGENIC  BACTERIA. 


A.  Bacillus  Subtilis.  B.  Micro-coccus  Ureee. 


A.  Bacillus  subtilis:   (a)  Culture  tube;  (b)  Cells. 

B.  Micrococcus  urese;    (a)  Culture  tube;  (b)  cells. 


A.  Sarcina  Lutea.  B.  Spirillum  Bubrum. 


A.  Sarcina  lutea:   (a)  Culture  tube;  (b)  Cells. 

B.  Spirillum  rubrum:    (a)  Culture  tube;  (b)  Cells. 

[163] 


1 64:  BACTERIOLOGY. 


CHAPTER  XXVIII. 
PATHOGENIC  BACTERIA. 

In  all  practical  work  with  pathogenic  bacteria,  more  than  ordi- 
nary care  should  be  used.  While  the  danger  attending  such  work 
should  not  be  unduly  magnified,  the  student  will  do  well  to  attend 
carefully  to  any  abrasions  on  the  skin;  he  should  be  scrupulously 
neat  and  cleanly,  not  allowing  the  material  used  to  be  carelessly  scat- 
tered; he  should  dispose  of  all  material  as  soon  as  used,  and  care- 
fully cleanse  the  hands  at  the  close  of  each  period.  It  is  doubt- 
less true  that  Bacillus  mallei  has  caused  the  death  of  more  bac- 
teriologists from  accidental  infection  than  all  other  species  to- 
gether. The  diseases  known  to  be  produced  in  man  by  bacteria  are 
tuberculosis,  leprosy,  glanders,  anthrax,  tetanus,  erysipelas,  gonor- 
rhoea, pneumonia,  influenza,  diphtheria,  typhoid  fever,  Asiatic  chol- 
era, relapsing  fever,  malignant  edema,  bubonic  plague,  and  sup- 
puration. It  is  believed  that  some  kind  of  micro-parasite  will  be 
found  to  be  the  specific  cause  of  each  of  the  following  diseases — viz., 
syphilis,  mumps,  smallpox,  chicken  pox,  measles,  scarlet  fever,  yel- 
low fever,  whooping  cough,  and  others.  The  limited  space  of  this 
Manual  will  allow  but  a  brief  discussion  of  a  few  of  the  more  im- 
portant species. 

I.  Bacillus  Tuberculosis. 

This  species  is  the  recognized  cause  of  consumption,  or  tubercu- 
losis. It  is  a  non-motile  facultative  saprophyte,  and  consists  of 
slender,  beaded  staves.  It  may  be  cultivated  on  glycerine  agar-agar, 
growing  best  at  37  degrees  Centigrade.  It  -reproduces  by  fission, 
and  probably  by  spore-formation.  It  is  also  pathogenic  to  a  num- 
ber of  animals.  Man  may  become  infected  through  wounds,  through 
nutrition — such  as  the  milk  of  tuberculous  cows — and  by  inhala- 
tion. The  sputum  of  the  consumptive,  if  not  properly  destroyed, 
dries  and  becomes  pulverized.  As  dust,  it  floats  in  the  atmosphere, 
is  inhaled,  and  under  suitable  conditions  produces  infection.  It  is 
doubtful  whether  any  one  is  immune  from  the  disease. 


PATHOGENIC  BACTERIA.  165 

Tuberculin  is  prepared  by  concentrating  with  heat  the  glycerine- 
bouillon,  containing  an  old  growth  of  tuberculosis,  and  filtering 
through  unglazed  porcelain.  It  is  used  for  the  detection  of  tuber- 
culosis in  animals.  The  suspected  animal  is  injected  with  the 
tuberculin,,  and  a  sudden  rise  of  temperature,  or  suppuration  of 
tubercular  formations,  may  be  considered  as  proof  that  the  ani- 
mal is  infected  with  the  disease. 

II.  Bacillus  Typhosus. 

The  bacillus  of  typhoid  fever  is  a  motile  parasite  found  in  the 
urine  and  fecal  discharges  of  typhoid  patients.  The  rods  have 
rounded  ends,  and  sometimes  grow  out  into  long  filaments.  It  pro- 
duces a  whitish  growth  on  agar,  growing  best  at  35  degrees  Centi- 
grade. Spore-formation  has  not  been  observed.  It  may  be  stained 
with  aqueous  solutions  of  fuchsin,  methylene  blue  and  gentian- 
violet. 

The  detection  of  typhoid  in  a  patient  may  be  made  by  adding  to 
some  serum  obtained  from  his  blood  a  'quantity  of  pure  culture.  It 
the  patient  has  the  disease,  the  motile  germs  will  soon  cease  their 
movements.  Flagella  may  be  demonstrated  by  method  No.  13. 

III.  Bacillus  Pyocyanus. 

This  species  is  an  actively-motile  aerobic  parasite,  presenting 
very  short,  slender  staves.  It  is  found  in  green  pus,  and  produces  a 
greenish- white  growth  on  agar-agar  at  the  room  temperature.  It 
may  be  stained  with  aqueous  fuchsin. 

IV.  Bacillus  Anthracis. 

This  bacillus  is  the  specific  cause  of  anthrax  in  cattle  and  the 
so-called  "  wool-sorter's  disease  "  in  men.  It  occurs  in  rods,  which 
have  truncate  ends  (slightly  indented),  and  generally  grow  out 
into  long  filaments.  It  produces  a  dry,  easily-detached  growth  on 
agar,  and  readily  liquefies  gelatin.  Its  movements  are  rotary.  The 
spores  are  ovoid,  may  be  central  or  polar,  and  are  very  resisting, 
having  been  known  to  live  twenty  years.  It  stains  well  with  aque- 
ous fuchsin  or  gentian- violet. 


166  BACTERIOLOGY. 

V.  Bacillus  Diphtherise. 

This  is  found  in  diphtheretic  membrane.  It  is  a  non-motile,  aero- 
bic species.  On  agar  it  produces  a  yellowish- white  growth,  with  cre- 
nated  edges.  The  rods  are  straight,  or  curved,  and,  when  stained, 
often  present  the  appearance  of  a  dumb-bell,  owing  to  the  deeper 
staining  of  the  polar  protoplasm.  It  grows  best  at  35  degrees  Cen- 
tigrade, and  stains  well  with  Loffler's  methylene  blue. 

The  antitoxin  of  diphtheria  is  produced  by  inoculating  a  horse 
with  a  small  amount  of  diphtheria  toxin  and  following  this  up  with 
an  increased  dose  every  six  days,  until  upwards  of  1,000  c.c.  can 
be  introduced  at  a  time.  As  a  result  of  this,  the  serum  of  the  blood 
becomes  immune  to  the  influence  of  the  toxin.  A  portion  of  the 
blood  is  then  removed  from  the  jugular  vein  of  the  horse,  and,  after 
coagulation,  the  serum  is  tested,  bottled,  and  sold  in  so-called  units 
of  strength.  A  unit  of  antitoxin  has  been  tersely  denned  by  Mac- 
Farland  as  "ten  times  the  least  amount  of  antitoxic  serum  that 
will  protect  a  standard  (300-gram)  guinea  pig  against  ten  times  the 
least  certainly  fatal  dose  of  diphtheria  toxin."  A  child  of  the  writer 
was  supposed  to  have  diphtheria,  bacteriological  tests  made  imme- 
diately proving  the  suspicion  to  be  well  founded.  Within  twenty- 
four  hours  of  the  first  appearance  of  the  diphtheretic  membrane, 
100  units  of  antitoxin  were  administered,  and  in  three  days  the  child 
was  considered  well. 

VI..  Staphylococcus  Pyogenes  Aureus. 

This  species  occurs  in  suppurations.  The  cells  are  spherical  in 
form  and  occur  singly,  or  in  clusters  resembling  bunches  of  grapes, 
called  zooglcese.  It  is  a  non-motile  anaerobic  facultative  parasite. 
It  produces  a  yellowish  growth  on  agar,  grows  at  the  room  tem- 
perature, liquefies  gelatin,  and  stains  well  with  aqueous  solutions. 

VII.  Streptococcus  Pyogenes. 

Streptococcus  pyogenes  is  found  in  erysipeloid  suppurations.  The 
cells  are  spherical,  and  occur  in  pairs  and  chains.  It  is  a  non-mo- 
tile facultative  anaerobe,  growing  best  at  35  degrees  Centigrade, 
producing  a  grayish- white  line  on  agar-agar.  It  stains  well  with 
aqueous  fuchsin,  or  gentian-violet. 


PATHOGENIC  BACTERIA.  167 

VIII.  Diplococcus  Pneumoniae. 

This  is  found  in  normal  saliva  and  in  the  sputum  of  croupous 
pneumonia.  The  cells  are  lance-shaped,  occurring  in  pairs,  sur- 
rounded by  a  capsule.  It  is  a  non-motile  facultative  saprophyte,  and 
produces  round,  grayish- white  colonies  on  nutrient  gelatin,  and  is 
non-liquefying.  It  may  be  stained  by  Gram's  method  or  with  the 
aqueous  solutions  of  aniline  dyes.  Injected  into  a  mouse,  it  pro- 
duces spetic93mia. 

IX.  Bacillus  Coli  Commune. 

The  colon  bacillus  is  found  associated  with  typhosus  in  typhoid 
fever,  and  with  Micrococcus  urcw  in  cystitis.  It  is  recognized  as 
the  cause  of  most  of  the  summer  complaints  among  children,  and  is 
almost  invariably  found  in  the  feces  of  healthy  persons.  It  is  mo- 
tile, grows  luxuriantly  on  ordinary  media;  produces  acids,  gases, 
and  indol;  coagulates  milk,  and  does  not  react  with  typhoid  blood. 
It  may  be  stained  with  fuchsin  or  gentian- violet. 

X.  Micrococcus  Gonorrhoeae, 

This  microbe  is  the  cause  of  gonorrhoea.  It  occurs  in  gonorrhceal 
discharges  from  the  urethra,  the  somewhat  hemispherical  cells  oc- 
curring on  the  surfaces  of  epithelial  cells,  or  in  pus-cells  in  pairs 
or  tetrads.  It  is  a  non-motile  facultative  anaerobe.  The  cocci  do 
not  stain  by  Gram's  method,  but  may  be  stained  with  Loffler's 
methylene  blue  or  aqueous  solutions  of  fuchsin  and  gentian-violet. 
It  does  not  grow  upon  gelatin. 

Other  species  which  may  be  studied  are  the  Bacillus  tetani  of 
tetanus,  Bacillus  influenza  of  influenza,  Baccillus  leprce  of  leprosy, 
Bacillus  mallei  of  glanders,  Spirillum  cholerce  of  cholera. 

Laboratory  exercise  No.  58. — StapJiylococcus  pyogenes  aureus.  Make  a 
systematic  study  of  this  species  and  write  out  a  full  outline  according* 
to  the  form  given  on  page  155.  Stain  by  method  No.  10.  and  study  with 
one-twelfth  oil-immersion  objective.  Make  out  single  cells  and  a  zo- 
oglcea. 

Laboratory  exercise  No.  59. — Streptococcus  pyogenes.  Make  a  sys- 
tematic study  of  this  species,  preparing  an  outline  and  making  the 
required  drawings.  Stain  with  aqueous  or  carbol  fuchsin.  Observe 
single  cells  and  slender  bead-like  filaments. 


168  BACTERIOLOGY. 

Laboratory  exercise  No.  60. — Micrococcus  gonorrhaxv.  Make  a  cover- 
glass  preparation  from  gonorrhceal  discharges  and  stain  with  Loffler's 
methylene  bine  or  carbol  fuchsin,  method  No.  10.  The  hemispherical 
cocci  will  be  found  in  pairs  or  tetrads  on  epithelial  cells  or  within  pus 
cells. 

Laboratory  exercise  No.  61. — Bacillus  tuberculosis.  Make  a  rather 
thick  smear  of  tubercular  sputum  upon  a  cover-glass,  dry  thoroughly, 
and  stain  by  method  No.  15.  Observe  the  slender,  beaded,  somewhat 
curved  rods.  Find  two  attached  by  their  extremities  forming  a  V-shape. 
Account  for  the  beaded  appearance. 

Laboratory  exercise  No.  62. — Bacillus  typhosus.  Make  a  systematic 
study  of  this  species  and  prepare  an  outline  of  your  work.  Observe  the 
motility  of  vegetative  specimens.  Demonstrate  flagella,  method  No.  13. 
Make  a  permanent  preparation,  staining  with  gentian-violet.  Look  for 
small  oval  spaces  in  the  ends  of  some  of  the  degenerated  bacilli. 

Laboratory  exercise  No.  63. — Bacillus  anthracis.  Make,  a  systematic 
study  of  this  species  and  prepare  an  outline.  Stain  a  permanent  prepa- 
ration with  gentian-violet.  Make  a  study  of  the  long  filaments.  Dem- 
onstrate spores  by  method  No.  12.  Harden,  embed,  and  section  the 
heart  and  lungs  of  a  mouse  that  has  been  killed  by  Bacillus  anthracis, 
and  stain  by  method  No.  16.  Search  for  bacteria. 

Laboratory  exercise  No.  64. — Bacillus  coli  commune.  Make  a  sys- 
tematic study  of  the  colon  bacillus.  State  all  the  points  of  difference 
between  this  species  and  Bacillus  typhosus.  Stain  your  permanent 
preparation  with  fuchsin  or  gentian-violet.  Make  drawings  of  all  spe- 
cies studied. 

Laboratory  exercise  No.  65. — Bacillus  diphtheriae.  Make  a  study  of 
cultures  of  the  diphtheria  bacillus  on  different  media.  Describe  the 
process  of  making  a  bacteriological  diagnosis  of  diphtheria.  Stain  a 
cover-glass  preparation  with  Loffler's  methylene  blue  and  make  a  study 
of  the  cells.  Observe  the  dumb-bell  forms.  A  good  lens  will  always 
exhibit  complete  rods,  showing  that  the  protoplasm  of  the  polar  ends 
is  connected.  Search  for  involution  forms,  also  for  three  or  four  cells 
joined  by  their  extremities,  noting  that  no  chains  are  formed.  Draw- 
ing. 


PATHOGENIC  BACTERIA. 


Diagrams  Showing  Cells,  Spores,  etc. 


A.  Staphylococcus  pyogenes  aureus;  B.  Streptococcus  pyogenes;  C.  Micrococcus  gonorrhoeas; 
D.  Bacillus  tuberculosis. 


Diagrams  Showing  Cells,  Spores,  etc. 


. 

A.  Bacillus  typhosus;    B.  Bacillus  anthracis;    G.  Bacillus  coli  commune;   D.  Bacillus  cliph- 
theriae. 


1713  BACTERIOLOGY. 


CHAPTEE  XXIX. 

IMMUNITY,  TOXINS,  ETC.— GERMICIDES,  ANTISEPTICS,  ETC. 

Ptomaines. — This  term  applies  to  all  compounds  of  a  basic  na- 
ture produced  by  the  agency  of  bacteria,  They  act  upon  the  sys- 
tem to  produce  the  symptoms  of  the  diseases  ascribed  to  the  species 
through  whose  agency  they  are  manufactured. 

Toxalbumins. — These  are  proteid  poisons  produced  by  bacteria, 
and  they  give  rise  to  the  symptoms  of  the  larger  number  of  infec- 
tious diseases. 

Leucomaines  have  been  defined  as  "  basic  substances  which  re- 
sult from  tissue  metabolism  in  the  body/' 

Toxins, — This  is  a  general  term  applied  to  all  poisons  produced 
by  bacteria,  and  especially  to  those  of  unknown  composition. 

Antitoxins. — Bacteria  also  produce  another  class  of  compounds 
known  as  antitoxins.  These  act  upon  the  tissues  in  such  a  way 
as  to  prevent  bacterial  infection. 

Immunity. — This  term  is  applied  to  the  power  of  resistance  to 
bacterial  infection  which  may  be  exerted  by  an  individual  man  or 
animal.  This  may  be  natural ;  or  it  may  be  acquired  by  disease,  ac- 
climatization, vaccination,  the  injection  of  antitoxins,  and  other 
means. 

An  antiseptic  is  a  substance  which  simply  retards  the  growth  of 
bacteria. 

A  germicide  is  a  substance  which  will  kill  bacteria,  The  term 
"  disinfectant"  has  the  same  significance.  Among  the  commonly  used 
and  most  effective  germicides  may  be  named  the  following:  Car- 
bolic acid,  mercuric  chloride,  silver  nitrate,  formaldehyde,  sulphur 
dioxid,  calcium  hypochlorite,  lime,  potassium  permanganate,  and 
copper  sulphate. 

For  the  destruction  of  the  sputum  of  consumptives  and  the 
evacuations  of  cholera  and  typhoid  patients,  Crookshank  recom- 
mends the  use  of  carbolic  acid,  one  in  twenty,  or  a  strong  solution 
of  chloride  of  lime.  Disinfection  of  the  skin  is  often  difficult,  as  a 
number  of  species  are  of  frequent  occurrence  upon  its  surface,  such 


IMMUNITY,  TOXINS,  ETC.  171 

as  Streptococcus  pyogenes,  Staphylococcus  pyogenes  aureus  (also 
albus  and  citrous),  Bacillus  tuberculosis,  Bacillus  pyocyanus,  and 
others.  Staphylococcus  epidermidis  albus  finds  its  normal  habitat 
in  the  skin.  Under  ordinary  circumstances,  sponging  the  skin  with 
carbolic  acid,  one  in  forty,  or  rinsing  it  in  bichloride  of  mercury, 
1  in  1,000,  will  give  satisfactory  results. 

For  the  disinfection  of  wounds,  hydrogen  peroxide  is  recom- 
mended. As  a  wash  for  the  mouth  and  throat  in  cases  of  inflamma- 
tion, abrasion,  and  suppuration,  a  weak  solution  of  permanganate 
of  potash  will  be  found  very  efficient  when  used  as  a  gargle. 

Fetri  Dish. 


Bausch  &  Lomb  Optical  Co. 


MEMORANDA. 


F=»  A.  «  T     I  V. 

URINALYSIS. 

The  clinical  significance  of  urinalysis  renders  this  subject  of 
paramount  importance  to  the  physician.  Only  a  bare  outline  is 
here  given  of  some  of  the  important  processes  of  physical  and  chem- 
ical urinalysis. '  In  the  preparation  of  this  outline  Purdy's  "  Prac- 
tical Urinalysis  and  Urinary  Diagnosis  "  has  been  consulted.  Those 
who  may  contemplate  pursuing  these  investigations  more  exhaust- 
ively will  not  be  disappointed  if  they  secure  this  admirable  text. 
The  microscopical  examination  of  urine  is  valuable  in  demonstrat- 
ing pus,  bacteria,  animal  parasites,  blood,  fat,  epithelium,  inorganic 
crystals,  and  other  products,  thus  affording  very  valuable  assistance 
in  the  detection  of  abnormal  conditions.  The  few  practical  exer- 
cises pointed  out  in  this  brief  discussion  are  only  suggestive  of  the 
field  which  might  be  explored  by  the  ambitious  student. 


CHAPTER  XXX. 

PHYSICAL,  CHEMICAL,  AND  MICROSCOPICAL  URINALYSIS. 
1.  PHYSICAL  URINALYSIS. 

The  physical  examination  of  urine  includes  the  following  deter- 
minations : 

1.  The  amount  voided  in  twenty-four  hours. — This  determina- 
tion is  important  as  a  basis  upon  which  to  estimate  the  quantity  of 
solid  matter  eliminated  in  a  given  period.     It  also  indicates  the 
possible  presence  or  absence  of  such  diseases  as  uraemia,  diabetes, 
and  Bright's  disease.     The  normal  quantity  passed,  in  twenty-four 
hours  ranges  from  1,000  c.c.  to  2,000  c.c.,  the  average  in  a  healthy 
person  being  1,500  c.c. 

2.  Odor. — The  odor  may  be  aromatic,  ammoniacaL,  putrid,  or 
scarcely  perceptible.       The  odor  of  freshly-voided  normal  urine  is 

[172] 


PHYSICAL  URINALYSIS.  173 

slightly  aromatic.     A  putrid  odor  indicates  tissue  degeneration  or 
the  decomposition  of  the  urine  within  the  body. 

3.  Color. — The  color  of  normal  urine  ranges  from  that  of  water, 
through  the  yellows,  to  reddish  brown,  the  average  being  straw,,  or 
amber,  color.     The  color  is  due  to  certain  pigments.     Concentrated 
urine  is  more  highly  colored  than  that  of  low  specific  gravity.     Ab- 
normal urine  exhibits  greater  fluctuations  in  color  than  that  of 
health.     Red  may  indicate  the  presence  of  blood;  a  black  color  in- 
dicates a  certain  form  of  cancer;  green  indicates  jaundice,  and 
occurs  sometimes  in  diabetes ;  blue  occurs  in  cholera  and  typhus. 

4.  Transparency. — Normal   urine   is  transparent   when   voided, 
becoming  cloudy  after  standing,  owing  to  the  action  of  bacteria. 
Pathological  urine  is  often  cloudy  when  first  obtained,  due  to  the 
action  of  bacteria,  the  presence  of  blood,  pus,  etc.,  and  the  precipi- 
tation of  salts.     Heat  removes  cloudiness  due  to  precipitated  urates, 
but  not  when  caused  by  bacteria.,  pus,  or  precipitated  phosphates. 
Acids  will  clear  up  any  cloudiness  due  to  precipitated  phosphates, 
but  will  increase  turbidity  arising  from  bacteria,  albuminous  casts, 
and  pus. 

5.  Chemical  reaction, — This  test  consists  in  finding  the  action  of 
urine  on  litmus,  an  acid  urine  turning  blue  litmus  red,  and  that 
which  is  alkaline  changing  red  to  blue.     Normal  urine  is  acid,  the 
acidity  being  due  to  the  acid  sodium  phosphate.     Excessive  acidity 
is  calculated  to  irritate  the  urinary  passages  and  favors  the  forma- 
tion of  uric  acid  concretions.     Alkalinity  of  the  urine  may  be  due 
to  the  presence  of  ammonium  carbonate  (resulting  from  the  de- 
composition of  urea  by  the  agency  of  bacteria)  or  to  an  alkali  of 
sodium  or  potassium.     In  the  former  case  the  litmus  paper  turns 
red  again  upon  drying ;  in  the  latter  case  it  remains  blue  upon  dry- 
ing. 

6.  Specific  gravity. — Normal  urine   (1,500  c.c.)  has  a  specific 
gravity  ranging  from  1.015  to  1.025,  the  average  being  1.020,  water 
being  taken  as  the  standard.     Low  specific  gravity  may  indicate 
nephritis  and  organic  albuminuria,  though  in  functional  albuminu- 
ria  the  specific  gravity  is  above  normal.     High  specific  gravity  is 
suggestive  of  melituria,  and  when  it  reaches  1.030  there  is  indicated 


174  URINALYSIS. 

the  probable   presence   of  sugar.     The   determination   of   specific 
gravity  is  made  with  a  urinometer. 

7.  Solids. — Xormal  urine,  when  freshly  voided,  is  free  from  visi- 
ble solids,  save  a  few  epithelial  scales.  The  visible  solids  of  abnor- 
mal urine  may  be  estimated  by  means  of  the  centrifuge.  The  quan- 
tity of  invisible  solids  in  normal  or  pathological  urine  may  be  esti- 
mated by  multiplying  the  last  two  figures  of  the  number  represent- 
ing the  specific  gravity  by  2.33.  This  gives  the  number  of  grams 
in  a  liter  of  the  sample.  Thus,  in  urine  whose  specific  gravity  is 
1.030,  the  number  of  grams  of  solids  held  in  solution  would  be 
30X2.33,  or  69.9  grams.  The  amount  of  solids  eliminated  by  the 
urine,  1,500  c.c.  in  twenty-four  hours,  would  be  represented  by  the 
equation  :  20  X  2. 33  X  1 . 5  =  69. 9  grams.  The  quantity  of  solids  for 
twenty-four  hours  is  affected  by  age,  diet,  exercise,  etc.,  the  average 
quantity  for  a  person  of  145  pounds  being  61  grams.  A  reduction 
of  solids  indicates  renal  diseases  (with  a  tendency  toward  uraemia) 
and  defective  elimination.  The  importance  of  knowing  the  amount 
of  urine  passed  in  twenty-four  hours  is  evident. 

Laboratory  exercise  No.  66. — Make  a  physical  examination  of  some 
sample  of  urine,  performing*  all  the  tests  indicated  above. 

2.  CHEMICAL  URINALYSIS. 

1.  Urea,  CO  (NH2)2. — The  normal  quantity  of  urea  in  the  urine 
is  about  one-half  of  all  the  solid  constituents,  or  about  35  grams. 
It  is  formed  in  the  liver  as  the  result  of  destructive  metabolism  of 
the  tissues  and  the  splitting  up  of  nitrogenous  food  principles.  An 
excess  of  urea  occurs  in  acute  diseases,  such  as  fevers,  in  some  liver 
affections,  such  as  diabetes,  and  accompanies  excessive  physical  and 
mental  exertion,  and  indicates  tissue  waste  A  deficiency  occurs  in 
chronic  diseases.  The  average  elimination  of  urea  for  an  adult  for 
twenty-four  hours  is  estimated  at  33  grams.  The  percentage  in  the 
urine  is  estimated  by  means  of  the  Doremus  ureometer  as  indicated 
in  the  following  method :  Fill  the  long  arm  of  the  ureometer  with 
hypobromite.  By  means  of  the  graduated  pipette  add  1  c.c.  of 
urine  by  compressing  the  nipple  gently  and  steadily.  The  hypo- 
bromite causes  the  liberation  of  nitrogen  gas,  which  collects  in  the 


CHEMICAL  URINALYSIS.  175 

upper  end  of  the  cylinder.  The  readings  on  the  ureometer  will  in- 
dicate the  number  of  milligrams  of  urea  in  1  c.c. ;  from  this  deter- 
mination may  be  calculated  the  total  amount  eliminated  in  twenty- 
four  hours. 

Hypobromite  may  be  prepared  as  follows :  To  250  c.c.  of  water 
add  100  grams  of  sodium  hydrate.  When  ready  to  make  the  test, 
add  to  10  c.c  of  the  sodium  hydrate  1  c.c.  of  bromine,  and  then  a 
quantity  of  water  equal  to  this  mixture. 

2.  Uric  acid. — Uric  acid  is  a  nitrogenous  compound  supposed  to 
be  formed  in  the  liver  by  the  union  of  ammonia  and  lactic  acid. 
The  quantity  eliminated  in  twenty-four  hours  by  the  healthy  adult 
is  about  0.5  gram.     An  excess  occurs  in  leukaemia,  fevers,  lung  and 
heart  diseases,  tumors,  etc.;   an  absence  of  uric  acid   occurs  in 
Bright's  disease,  gout,  and  other  affections. 

A  qualitative  test  may  be  made  by  strongly  acidulating  with  hy- 
drochloric acid  a  beakerful  of  urine.  After  standing  twenty-four 
hours,  uric  acid  crystals  will  be  deposited,  which  may  be  examined 
with  the  microscope. 

3.  Glucose. — Sugar  occurs  temporarily  in  the  urine  with  such 
diseases  as  cholera,  gout,  intermittent  fever,  etc.     Its  presence  be- 
comes persistent  in  diabetes.     It  may  be  detected  by  Fehling's  solu- 
tion, Haynes'  test,  fermentation  test,  etc. 

Fehling's  solution  is  prepared  by  dissolving  6.9  grams  of  copper 
sulphate  in  100  c.c.  of  distilled  water.  Then  a  second  solution  is 
prepared  by  dissolving  34  grams  of  potassium  sodium  tartrate  and 
25  grams  of  potassium  hydrate  in  100  c.c.  of  water.  In  making  the 
test,  place  about  5  c.c.  of  each  of  these  solutions  in  separate  test 
tubes,  heat  to  boiling,  and,  after  adding  one  to  the  other,  add  a  few 
drops  of  the  suspected  urine.  If  a  yellowish-red  precipitate  is 
formed,  it  indicates  the  presence  of  sugar. 

Hay  lies'  solution  is  prepared  by  mixing  30  grains  of  copper  sul- 
phate with  one-half  ounce  of  distilled  water,  then  adding  one-half 
ounce  of  pure  glycerine,  and,  after  mixing,  adding  five  ounces  of 
liquor  potassse  The  test  is  made  by  boiling  five  to  ten  cubic  centi- 
meters of  this  solution  in  a  test  tube,  and  adding  six  to  eight  drops 


176  URINALYSIS. 

of  the  suspected  urine.     Boil  again,  and,  if  sugar  be  present,  a  yel- 
lowish-red precipitate  will  be  formed. 

A  quantitative  test  for  sugar  may  be  made  with  the  fermentation 
saccharometer  as  follows:  To  10  c.c.  of  urine  add  one  gram  of 
Fleischmann's  yeast;  shake  thoroughly  in  a  test  tube;  pour  the 
mixture  into  the  saccharometer.  The  yeast  produces  the  decompo- 
sition of  the  sugar  with  the  formation  of  carbonic  acid  gas.  The 
quantity  of  gas  evolved  indicates  the  amount  of  sugar  present,  and 
may  be  determined  by  the  readings  of  the  graduated  scale. 

4.  Albumin. — The  presence  of  albumin  in  urine  may  be  due  to 
degeneration  of  the  kidney  tissues,  excessive  blood  pressure,  or  an 
increased  diff  usibility  of  the  serum-albumin  of  the  blood.    It  is  prob- 
ably more  often  due  to  kidney  degeneration,  and  in  such  cases  is  in- 
dicative of  chronic  albuminuria,  known  as  Bright's  disease.     It  may 
be  detected  by  the  following  methods : 

(1)  Heat  Test. — Pour  into  a  test  tube  about  10  c.c.  of  the  sus- 
pected urine;  heat  the  upper  portion  to  boiling.     If  a  cloudiness 
appears,  which  is  not  removed  by  nitric  acid,  albumin  is  present. 

(2)  Nitric  Acid  Test. — Pour  into  a  test  tube  5  c.c.  of  nitric  acid; 
then,  with  a  pipette,  add,  drop  by  drop,  some  of  the  suspected  urine, 
allowing  it  to  run  down  the  side  of  the  tube.     If  albumin  is  present, 
a  white  ring  will  be  formed  at  the  plane  of  juncture  of  the  two 
fluids. 

(3)  Quantitative  Test. — Using  Esbach's  albuminometer,  fill  the 
tube  with  urine  to  the  graduation  U;  then  add  the  test  solution 
(10  grams  picric  acid,  20  grams  citric  acid,  water  to  make  one  liter) 
to  fill  the  tube  to  graduation  E.     Cover  the  end  of  the  tube  and 
shake  the  contents  thoroughly:  close  the  tube  with  rubber  stopper, 
and  set  aside  for  twenty-four  hours.     The  precipitated  albumin  can 
then  be  estimated  from  the  graduated  scale,  each  graduation  indi- 
cating one  gram  of  albumin  in  a  liter  of  urine. 

5.  Chlorides. — The  quantity  of  chlorides  eliminated  by  the  urine 
in  twenty-four  hours  is  from  six  to  ten  grams.     When  the  amount 
becomes  less  than  five  grams,  it  indicates  weakness  of  digestion. 
An  excessive  excretion  occurs  in  diabetes,  and  is  considered  a  favor- 


CHEMICAL  URINALYSIS.  ITT 

able  sign  in  dropsical  conditions.  The  presence  of  chlorides  may 
be  tested  by  acidulating  with  nitric  acid  and  adding  silver  nitrate. 
A  white  precipitate  of  chlorides  is  formed. 

Quantitative  test:  Dilute  10  c.c.  of  urine  with  100  c.c.  of  water; 
add  a  few  drops  of  potassium  chromate  solution;  then  add  slowly 
a  solution  of  silver  nitrate  (17  grams  to  a  liter  of  water)  until  the 
color  of  the  solution  changes  from  yellow  to  red.  Each  c.c.  of  silver 
nitrate  (standard  solution)  used  will  precipitate  0.00354  gram  of 
chlorine,  from  which  may  be  estimated  the  percentage  by  weight 
of  chlorine  in  the  urine. 

6.  Phosphates. — The  earthy  phosphates  are  those  of  calcium  and 
magnesium;  the  alkaline  phosphates  are  those  of  sodium  and  potas- 
sium ;  triple  phosphate  is  ammonio-magnesium  phosphate ;  the  acid 
phosphates  of  the  alkalies  give  the  acid  reaction  to  the  urine,  and 
are  represented  by  the  formulas  NaH2  P04  and  KH2  P04.  An 
excess  of  phosphates  occurs  in  diabetes.  A  diminution  generally 
occurs  in  nephritis,  gout,  rheumatism,  and  acute  infectious  diseases. 

The  earthy  phosphates  may  be  detected  by  adding  ammonium 
hydrate  and  gently  heating;  a  white  precipitate  is  formed,  which 
is  dissolved  by  the  addition  of  acetic  acid.  A  quantitative  deter- 
mination may  be  made  by  filling  a  test  tube  whose  diameter  is  two 
centimeters  with  urine  to  the  depth  of  5.3  centimeters;  to  this  add 
a  few  drops  of  ammonium  hydrate  and  heat  until  the  phosphates  are 
precipitated;  set  aside  and  in  fifteen  minutes  examine.  If  the 
height  of  sediment  be  1  centimeter,  the  quantity  of  earthy  phos,- 
phates  is  normal,  but  diminished  or  increased  if  the  height  should 
be  less  or  greater  than  1  centimeter. 

To  determine  approximately  the  quantity  of  alkaline  phosphates, 
proceed  as  follows :  Kemove  the  earthy  phosphates  by  precipitation 
and  filtration,  and  to  10  c.c.  of  the  filtered  urine  add  3  c.c.  of  mag- 
nesium mixture.  Magnesium  fluid  is  prepared  by  dissolving  magne- 
sium sulphate  and  ammonium  chloride,  one  part  each,  in  eight  parts 
of  distilled  water  and  one  part  of  ammonium  hydrate.  The  amount 
of  turbidity  formed  by  the  precipitate  indicates  the  quantity  of 

alkaline  phosphates  present.     If  it  is  simply  milky,  the  quantity  is 
12 


178  URINALYSIS. 

normal;  if  heavy,  increased;  and  if  no  precipitate,  there  is  a  de- 
crease. 

7.  Sulphates. — The  total  amount  of  sulphuric  acid  in  combina- 
tion excreted  by  an  adult  in  twenty-four  hours  is  between  two  and 
three  grams.  An  increase  of  sulphates  occurs  in  serious  stoppages 
of  the  food  in  the  intestines,  the  pus  forming  diseases,  as  in  fetid 
bronchitis,  diphtheria,  etc.,  and  in  acute  fevers,  meningitis,  and 
rheumatism.  They  may  be  detected  by  adding  to  a  portion  of  the 
urine  one-third  the  amount  of  barium  chloride  acidulated  with  hy- 
drochloric acid.  A  white,  milky  precipitate  indicates  the  presence 
of  sulphates.  An  approximate  quantitative  determination  may  be 
made  as  follows :  To  10  c.c.  of  urine  add  3  c.c.  of  barium  chloride 
solution,  which  is  prepared  by  mixing  four  parts  of  barium  chloride, 
one  part  of  hydrochloric  acid,  and  sixteen  parts  of  distilled  water. 
If  a  milky  turbidity  results,  the  quantity  of  sulphates  is  normal; 
if  the  precipitate  is  heavy,  having  the  consistency  of  cream,  it  is  in- 
creased. 

Laboratory  exercise  No.  67.—  Chemical  examination.  Make  an  analy- 
sis of  a  sample  of  urine  by  the  chemical  tests  suggested  above.  Write 
out  your  analysis  in  systematic  form. 

3.  MICROSCOPICAL  URINALYSIS. 

The  microscopical  examination  of  urine  is  of  value  in  confirming 
the  results  of  physical  and  chemical  analyses  and  in  throwing  light 
upon  certain  pathological  conditions — light  obtainable  from  no 
other  source.  The  sediments  of  urine  may  be  organized  or  unorgan- 
ized. Organized  sediments  comprise  epithelium,  blood,  pus,  tubu- 
lar casts,  spermatozoa,  bacteria,  and  vermes.  The  unorganized 
sediments  comprise  crystals  of  the  phosphates,  urates,  etc.,  amor- 
phous compounds,  and  inorganic  concretions. 

UNORGANIZED  SEDIMENTS. 

Among  some  of  the  forms  of  crystals  which  may  be  demonstrated 
by  microscopical  urinalysis  are  those  of  calcium  oxalate  (Fig.  1), 
triple  phosphate  (Fig.  2),  uric  acid  (Fig.  3),  leucin  and  tyrosin 
(Fig.  4),  nitrate  of  urea  (Fig.  5),  calcium  sulphate  (Fig.  6),  cal- 
cium phosphate  (Fig.  7),  and  hamiin  (Fig.  8). 


UNORGANIZED  SEDIMENTS. 

Fig.  1  Fig.  2 


Calcium  Oxalate. 


Triple  Phosphate. 


Fig.  3 


Fig.  4 


Uric  Acid. 


Fig.  5 


Nitrate  of  Urea. 


Fig,  7 


Calcium  Phosphate. 


Fig.  6 


Calcium  Sulphate. 


Fig.  8 


Haemin  Crystals. 


[179] 


180  URINALYSIS. 

Amorphous  sediments,  such  as  mates,  phosphates,  etc.,  are  of 
occasional  occurrence. 

Laboratory  exercise  No.  68. — Organic  sediments.  Obtain  some  cys- 
titic  urine  by  means  of  a  pipette;  apply  a  drop  of  the  sediment  to  the 
slide;  cover  and  search  for  epithelium,  noting-  the  forms  of  the  cells; 
search  also  for  pus  and  bacteria.  Of  what  significance  are  these  ele- 
ments ? 

Bacillus  coli  commune,  Micrococcus  urece,  and  the  species  of 
Staphylococcus  invariably  occur  in  cystitic  urine.  What  other  ele- 
ments do  you  observe  ?  Make  a  cover-glass  preparation,  and  stain 
with  gentian- violet.  Mount  in  water,  and  make  a  search  for  pus, 
bacteria,  epithelium,  blood,  crystals,  and  other  structures. 

Obtain  samples  of  urine  from  cases  of  nephritis,  Bright ?s  disease, 
etc.  Examine  the  sediments  by  the  usual  method,  and  demonstrate 
epithelium,  blood  casts,  bacteria,  etc.,  such  as  may  be  present. 
Patty,  granular,  epithelial,  and  blood  casts  may  be  easily  demon- 
strated. Hyaline  casts  should  be  precipitated  by  means  of  a  centri- 
fuge. A  drop  of  the  sediment  is  placed  upon  a  slide  containing 
a  cell,  covered,  and  then  examined.  The  casts  are  of  small  or  large 
diameter  and  transparent. 

Laboratory  exercise  No.  69. — Crystals.  Allow  cystitic  urine  to  stand 
for  twenty-four  hours.  Examine  some  of  the  sediment  and  determine 
the  kinds  of  crystals  present  by  comparing  their  forms  with  those  of 
the  illustrations  on  page  179. 

Clean  five  slips;  upon  each  place  a  drop  of  urine.  Allow  the 
first  to  dry  without  adding  any  reagent;  to  the  second  add  a 
small  drop  of  ammonium  hydrate;  to  the  third,  a  drop  of  hydro- 
chloric acid;  to  the  fourth,  nitric  acid;  and  to  the  fifth,  dilute  sul- 
phuric acid.  When  these  preparations  are  dry,  or  nearly  so,  cover 
and  examine.  Preparation  No.  1  may  exhibit  crystals  of  calcium 
oxalate,  leucin,  tyrosin,  and  uric  acid ;  No.  2  will  exhibit  crystals  of 
triple  phosphate  (Fig.  2)  and  calcium  phosphate  (Fig.  7)  ;  No.  3 
may  illustrate  crystals  of  uric  acid  (Fig.  3)  ;  No.  4  will  exhibit 
nitrate  of  urea  (Fig  5)  ;  and  No.  5  will  show  crystals  of  calcium 
sulphate  ( Fig.  6 ) .  Determine  any  other  forms  which  may  be  ob- 
served. 


ORGANIZED  SEDIMENTS.  181 

ORGANIZED  SEDIMENTS. 

1.  Epithelium. — Epithelium  occurs  in  urine  as  isolated  cells;  or, 
occasionally,  groups  of  attached  cells  may  be  demonstrated.     In 
normal  urine  there  is  always  a  limited  number  of  epithelial  cells 
due  to  ordinary  desquamation,  but  under  pathological  conditions 
the  number  becomes  greatly  increased.     This  may  be  due  to  inflam- 
mation, suppuration,  friction,   and  the  action  of  bacteria.     The 
elements  from  the  renal  tubules  are  generally  small  round  cells, 
columnar  or  cuboidal  cells ;  those  from  the  excretory  duct  are  of  the 
tall  columnar  variety ;  and  those  from  the  pelvis,  ureter,  and  blad- 
der are  of  the  transitional  type,  exhibiting  irregular  forms — spindle- 
shaped,  polyhedral,  and  large  round  cells,  some  having  more  than 
one  nucleus,  and  some  exhibiting  pointed  processes ;  cells  from  the 
prostatic  portion  of  the  urethra  are  of  the  squamous  type,  while 
those  from  the  free  portion  are  low  columnar  cells.     In  the  female, 
squamous  epithelium  lines  the  entire  urethra. 

2.  Blood  (Fig.  10). — Blood  occurs  only  in  pathological  urine; 
it  may  be  detected  microscopically  by  the  presence  of  the  red  disks. 
These  are  known  by  their  form  and  the  absence  of  nuclei ;  they  sel- 
dom form  in  rouleaux,  but  often  exhibit  crenation.     Tuberculosis 
of  the  kidneys,  pyelitis,  cystitis,  and  other  affections  are  suggested 
by  the  presence  of  blood. 

3.  PUB  (Figs.  9  and  14). — Pus  consists  of  dead  or  dying  leuco- 
cytes, which  have  escaped  from  the  vascular  channels.     Leucocytes 
are  concerned  in  repairing  diseased  tissues  and  the  destruction  of 
microbes.     \7ast  numbers  die  in  the  conflict,  and  these  constitute 
pus.     Pus  cells  may  be  distinguished  from  other  elements  by  their 
size,  granular  appearance,  and  nuclei.     They  often  contain  several 
nuclei  in  each  cell  and  occasionally  exhibit  amoeboid  movement. 
Pus  is  invariably  present  in  cystitis,  gonorrhcea,  tuberculosis,  etc. 

4.  Casts. — These  originate  in  the  renal  tubules  and  comprise 
several  varieties :  Blood  casts,  epithelial  casts,  granular  casts,  fatty 
casts,  and  hyaline  casts. 

Blood  casts  (Fig.  13)  are  the  result  of  hemorrhage  in  the  urinary 
tubules,  and  indicate  such  infections  as  haematuria,  renal  congestion, 
and  acute  nephritis. 


ORGANIZED  SEDIMENTS. 


Fig.  9 


Fig.  10 


o 


Pus  Cells. 


1Z.4 


Stf*«    fi$f% 


Blood. 


Fig.  11 


Fig.  12 


Hyaline  Casts. 


Epithelial  Casts. 


Fig.  13 


Fig.  14 


Fig.  15 


Blood  Casts.  Pus  Showing  Amoeboid  Movement.  Granular  Casts. 


[182] 


ORGANIZED  SEDIMENTS.  183 

Epithelial  casts  (Fig.  12)  result  from  the  disintegration  of  the 
epithelium  of  the  renal  tubules;  their  presence  indicates  nephritis 
and  other  kidney  infections. 

Granular  casts  (Fig.  15)  result  from  the  disintegration  •  of  pas, 
epithelium,  and  blood,  and  are  indicative  of  pathological  conditions 
of  the  kidney. 

Fatty  casts  are  the  result  of  changes  in  the  kidney  which  indicate 
the  destruction  of  the  protoplasm  of  the  cells. 

Hyaline  casts  (Fig.  11)  are  probably  produced  by  the  coagulation 
of  certain  elements  of  the  blood  which  have  gained  access  to  the 
renal  tubules.  They  are  almost  colorless  and  difficult  of  demon- 
stration; their  presence  indicates  interstitial-nephritis. 

5.  Bacteria. — Normal  urine  is  free  from  bacteria,     The  species 
most  commonly  met  with  in  pathological  urine  are  Micrococcus 
urece,  Staphylococcus  pyogenes  aureus,  albus,  and  citreus,  Strepto- 
coccus pyogenes  and  Bacillus  coli  commune.     Bacillus  tuberculosis 
is  of  occasional  occurrence.     These  organisms  can  be  demonstrated 
by  the  usual  methods  of  staining. 

6.  Vermes. — Two  species  of  vermes  are  of  occasional  occurrence 
— namely,  Distoma  hwrnatobium  and  Filaria  sanguinis  Jiominis. 

Laboratory  exercise  No.  70. — Make  a  complete  analysis  of  some  sam- 
ple of  urine,  and  fill  out  the  form  presented  on  pages  184-185. 

MEMORANDA. 


184 


URINALYSIS. 
ANALYSIS  OF  URINE. 


Sample 

Physical  Tests. 

f  Normal  urine 

1.  Amount  in  24  hours. .  < 

^  Sample  examined  . . 

f  Normal  urine 

2.  Odor j 

(_  Sample  tested 

(  Normal  urine 

3.  Color •{ 

t  Sample 

f  Normal  urine 

4.  Transparency <^ 

t  Sample 

f  Normal  urine 

5.  Chemical  reaction  . . .  -j 

[  Sample 

f  Normal  urine 

6.  Specific  gravity «j 

[  Sample 

f  Normal 
f  Visible...  <| 

[_  Sample 

7.  Solids <[ 

f  Normal 
^  Invisible .  < 

[  Sample 

Chemical  Tests. 

f  Normal 

1.  Urea <^ 

[  Sample 

f  Normal 

2.  Uric  acid •{ 

t  Sample 

f  Normal 

3.  Glucose < 

[  Sample  . 

f  Normal 

4.  Albumin <j 

t  Sample 


ANALYSIS  OF  URINE. 


185 


5.  Chlorides. 


6.   Phosphates. 


7.  Sulphates 


Normal 
Sample 


Earthy  .. 


Normal 


Sample 


f  Normal 
I  Alkaline  .  \ 

[  Sample 


f  Normal 
[  Sample 


Microscopical  Tests. 

Small  round  cells , 

Tall  columnar 

1.  Epithelium •{   Transitional , 

Squamous 

Low  columnar 

2.  Blood 

3.  Pus 

f  Blood  casts 

Epithelial 

4.  Casts 4  Granular 

Fatty 

Hyaline.... 

5.  Bacteria , 

6.  Spermatazoa 

7.  Crystals 

8.  Amorphous  sediments 

Clinical  Significance  of  Examination. 

Respectfully, 


Date 


19. 


INDEX. 


PAGE 

Abbreviations  ............................  28 

Accessories  ...............................  13 

Adenoid  tissue  ...........................  68 

Adepose  tissue  ..................  .........  67 

Alimentary  tract  .........................  Ill 

Amoeba  ...................................  47 

Areolar  tissue  .............  .  ..........  ____  67 

Arteries  ..................................  93 

Bacteria  ..................................  143 

Classification  ........................  144 

Cultivation  of  ........................  151 

Distribution  ..........................  149 

Kinds  ................................  145 

Morphology  ..........................  145 

Non-pathogenic  ..........  _____  ......  160 

Numbers  .............................  149 

Pathogenic  ...........................  164 

Products  .............................  146 

Size  .....................  .  ............  149 

Study  of  ..............................  153 

Bacteriology  ...............  .  .............  143 

Basement  membrane  ____  ...........  .  .....  68 

Balsam  ...................................  34 

Blood  .....................................  55 

Bone  .....................................  70 

Brain  .....................................  85 

Brownian  movement  .....................  42 

Capillaries  ...............................  94 

Cartilage  .................................  69 


Cell 


35 


Contents  .............................  38 

Multiplication  .......................  40 

Wall  .................................  37 

Centering  ................................  19 

Centrifuge  ...............................  14 

Cerebellum  ...............................  86 

Cerebrum  ..  .............  ____  .............  87 

Clearing  ..................................  19 

Connective  tissue  .....................  ...  66 

Cowper's  glands  .........................  136 

Culture  media  ............................  151 

Dehydration  .............................  19 

Dentine  .........................  .  ........  72 

Drawings  .......................  .  ........  28 

Ear  .......................................  142 

Embedding  ...............................  17 


PAGE 

Embryology 54 

Endothelium 61 

Epithelium 61 

Euglsena 50 

Eye 141 

Fallopian  tube 138 

Fixation 18 

Fixatives  32 

Fixing 16 

Germicides 170 

Glands 101 

Hair 107 

Hanging-drop 153 

Hardening 16 

Heart 93 

Immunity 170 

Infiltrating 16 

Injecting 20 

Inoculation 152 

Intestine 114 

Irrigation 27 

Kidney 131 

Labeling 20 

Leucocytes 56 

Liver 118 

Lungs 128 

Lymphatic  system 96 

Medulla  oblongata 86 

Membranes 100 

Micromillimeter 100 

Microscope 8 

Microscopic  technique 16,  156 

Microtome 20 

Mould 154 

Mounting 20 

Muscle 75 

Nails 107 

Nerve  endings 88 

Nervous  systems 81 

Nervous  tissues 79 

Nose 142 

(Esophagus 113 

[1871 


188 


INDEX. 


PAGE 

Organs 53 

Ovary 137 

Pancreas 103 

Parotid  gland 102 

Parovarium 138 

Penis 137 

Plasraodium  malariae 57 

Plating 52 

Prostate  gland 136 

Protococcus 44 

Protoplasm 37 

Reagents 30 

Reproduction 40 

Sebaceous  gland 108 

Sectioning 18 

Skin 106 

Slipper  animalcule 49 

Spleen 98 

Spinal  cord 81 

Spirogyra 46 

Staining 19 


PAGE 

Staining  methods 23,  157 

Stains 30 

Stomach 113 

Sweat  glands 108 

Sympathetic  system 88 

Teeth 122 

Testis 135 

Thymusbody 98 

Tissues 20,  53 

Tongue 121 

Tonsils 98 

Toxins 170 

Ureters 133 

Urethra 133 

Uterus 138 

Urinalysis 172 

Vagina 139 

Veins 94 

Yeast...  ..  43 


MEMORANDA. 


MEMORANDA. 


MEMORANDA. 


MEMORANDA. 


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